Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

Characteristic	Locus
Inheritance	object > Mcp23xxx > Mcp23x0x > Mcp23x1x
Implements	IDigitalInputOutputController IDigitalInputController IDigitalOutputController ISpiPeripheral II2cPeripheral IDigitalInterruptController IPinController
Inherited Members	object.Equals(object) object.Equals(object, object) object.GetHashCode() object.GetType() object.MemberwiseClone() object.ReferenceEquals(object, object) object.ToString()
Namespace	Meadow.Foundation.ICs.IOExpanders
Assembly	Mcp23xxx.dll

Syntax

public abstract class Mcp23xxx : IDigitalInputOutputController, IDigitalInputController, IDigitalOutputController, ISpiPeripheral, II2cPeripheral, IDigitalInterruptController, IPinController

Constructors

Mcp23xxx(II2cBus, byte, IDigitalInterruptPort?, IDigitalOutputPort?)

Mcp23xxx base class constructor using I2C

Declaration

protected Mcp23xxx(II2cBus i2cBus, byte address, IDigitalInterruptPort? interruptPort = null, IDigitalOutputPort? resetPort = null)

Parameters

Type	Name	Description
II2cBus	i2cBus	The I2C bus
byte	address	The I2C address
IDigitalInterruptPort	interruptPort	Optional interrupt port, needed for input interrupts (pins 1-8)
IDigitalOutputPort	resetPort	Optional Meadow output port used to reset the mcp expander

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

Mcp23xxx(ISpiBus, IDigitalOutputPort, IDigitalInterruptPort?, IDigitalOutputPort?)

Mcp23xxx base class constructor using SPI

Declaration

protected Mcp23xxx(ISpiBus spiBus, IDigitalOutputPort chipSelectPort, IDigitalInterruptPort? interruptPort = null, IDigitalOutputPort? resetPort = null)

Parameters

Type	Name	Description
ISpiBus	spiBus	The SPI bus
IDigitalOutputPort	chipSelectPort	Chip select port
IDigitalInterruptPort	interruptPort	Optional interrupt port, needed for input interrupts (pins 1-8)
IDigitalOutputPort	resetPort	Optional Meadow output port used to reset the mcp expander

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

Fields

_lock

object for using lock() to do thread sync

Declaration

protected object _lock

Field Value

Type	Description
object

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

Properties

DefaultI2cAddress

The default I2C address for the peripheral

Declaration

public byte DefaultI2cAddress { get; }

Property Value

Type	Description
byte

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

DefaultSpiBusMode

The default SPI bus mode for the device

Declaration

public SpiClockConfiguration.Mode DefaultSpiBusMode { get; }

Property Value

Type	Description
SpiClockConfiguration.Mode

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

DefaultSpiBusSpeed

The default SPI bus speed for the device

Declaration

public Frequency DefaultSpiBusSpeed { get; }

Property Value

Type	Description
Frequency

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

NumberOfPins

The number of IO pins available on the device

Declaration

public abstract int NumberOfPins { get; }

Property Value

Type	Description
int

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

SpiBusMode

The SPI bus mode for the device

Declaration

public SpiClockConfiguration.Mode SpiBusMode { get; set; }

Property Value

Type	Description
SpiClockConfiguration.Mode

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

SpiBusSpeed

The SPI bus speed for the device

Declaration

public Frequency SpiBusSpeed { get; set; }

Property Value

Type	Description
Frequency

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

Methods

CreateDigitalInputPort(IPin, ResistorMode)

Creates a new DigitalInputPort using the specified pin

Declaration

public IDigitalInputPort CreateDigitalInputPort(IPin pin, ResistorMode resistorMode = ResistorMode.Disabled)

Parameters

Type	Name	Description
IPin	pin	The pin representing the port
ResistorMode	resistorMode	The port resistor mode

Returns

Type	Description
IDigitalInputPort	IDigitalInputPort

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

CreateDigitalInterruptPort(IPin, InterruptMode, ResistorMode)

Creates a new DigitalInputPort using the specified pin

Declaration

public IDigitalInterruptPort CreateDigitalInterruptPort(IPin pin, InterruptMode interruptMode = InterruptMode.None, ResistorMode resistorMode = ResistorMode.Disabled)

Parameters

Type	Name	Description
IPin	pin	The pin representing the port
InterruptMode	interruptMode	The port interrupt mode
ResistorMode	resistorMode	The port resistor mode

Returns

Type	Description
IDigitalInterruptPort	IDigitalInterruptPort

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

CreateDigitalInterruptPort(IPin, InterruptMode, ResistorMode, TimeSpan)

Creates a new DigitalInputPort using the specified pin

Declaration

public IDigitalInterruptPort CreateDigitalInterruptPort(IPin pin, InterruptMode interruptMode, ResistorMode resistorMode, TimeSpan debounceDuration)

Parameters

Type	Name	Description
IPin	pin	The pin representing the port
InterruptMode	interruptMode	The port interrupt mode
ResistorMode	resistorMode	The port resistor mode
TimeSpan	debounceDuration	The debounce duration

Returns

Type	Description
IDigitalInterruptPort	IDigitalInterruptPort

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

CreateDigitalInterruptPort(IPin, InterruptMode, ResistorMode, TimeSpan, TimeSpan)

Creates a new DigitalInputPort using the specified pin

Declaration

public IDigitalInterruptPort CreateDigitalInterruptPort(IPin pin, InterruptMode interruptMode, ResistorMode resistorMode, TimeSpan debounceDuration, TimeSpan glitchDuration)

Parameters

Type	Name	Description
IPin	pin	The pin representing the port
InterruptMode	interruptMode	The port interrupt mode
ResistorMode	resistorMode	The port resistor mode
TimeSpan	debounceDuration	The debounce duration
TimeSpan	glitchDuration	The glitch duration - not configurable on Mcp23xxx

Returns

Type	Description
IDigitalInterruptPort	IDigitalInterruptPort

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

CreateDigitalOutputPort(IPin, bool, OutputType)

Creates a new DigitalOutputPort using the specified pin and initial state

Declaration

public virtual IDigitalOutputPort CreateDigitalOutputPort(IPin pin, bool initialState = false, OutputType outputType = OutputType.OpenDrain)

Parameters

Type	Name	Description
IPin	pin	The pin representing the port
bool	initialState	Whether the pin is initially high or low
OutputType	outputType	The output type

Returns

Type	Description
IDigitalOutputPort	IDigitalOutputPort

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

GetAddressFromPins(bool, bool, bool)

Help method to get address from address pin configuration

Declaration

public static byte GetAddressFromPins(bool pinA0, bool pinA1, bool pinA2)

Parameters

Type	Name	Description
bool	pinA0	State of A0 address pin - true if high
bool	pinA1	State of A1 address pin - true if high
bool	pinA2	State of A2 address pin - true if high

Returns

Type	Description
byte	The device address

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

GetPin(string)

Get Pin by name

Declaration

public abstract IPin GetPin(string pinName)

Parameters

Type	Name	Description
string	pinName	The pin name

Returns

Type	Description
IPin	IPin object if found

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

IsValidPin(IPin)

Checks if a pin exists on the Mcp23xxx

Declaration

protected abstract bool IsValidPin(IPin pin)

Parameters

Type	Name	Description
IPin	pin

Returns

Type	Description
bool

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

ReadFromPorts(PortBank)

Reads a byte value from all of the pins. little-endian; the least significant bit is the value of GP0. So a byte value of 0x60, or 0110 0000, means that pins GP5 and GP6 are high.

Declaration

public byte ReadFromPorts(Mcp23xxx.PortBank bank = PortBank.A)

Parameters

Type	Name	Description
Mcp23xxx.PortBank	bank

Returns

Type	Description
byte	A little-endian byte mask of the pin values.

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

ReadPort(IPin)

Gets the value of a particular port. If the port is currently configured as an output, this will change the configuration.

Declaration

public bool ReadPort(IPin pin)

Parameters

Type	Name	Description
IPin	pin

Returns

Type	Description
bool

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

ResetMcp()

Reset the MCPxxxx expander Requires using a reset port

Declaration

public void ResetMcp()

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

ResetPin(IPin)

Sets the pin back to an input

Declaration

protected void ResetPin(IPin pin)

Parameters

Type	Name	Description
IPin	pin

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

SetPortDirection(IPin, PortDirectionType)

Sets the direction of a port

Declaration

public void SetPortDirection(IPin pin, PortDirectionType direction)

Parameters

Type	Name	Description
IPin	pin	The pin representing the port
PortDirectionType	direction	The port direction (input or output)

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

WriteToPort(IPin, bool)

Sets a particular pin's value. If that pin is not in output mode, this method will first set its mode to output.

Declaration

public void WriteToPort(IPin pin, bool value)

Parameters

Type	Name	Description
IPin	pin	The pin to write to.
bool	value	The value to write. True for high, false for low.

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

WriteToPorts(byte)

Outputs a byte value across all of the pins by writing directly to the output latch (OLAT) register

Declaration

public void WriteToPorts(byte mask)

Parameters

Type	Name	Description
byte	mask

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18

Events

InputChanged

Raised when the value of any pin configured for input interrupts changes This provides raw port state data from the MCP23xxx It's highly recommended to prefer using the events exposed on the digital input ports instead.

Declaration

public event EventHandler<IOExpanderInputChangedEventArgs> InputChanged

Event Type

Type	Description
EventHandler<IOExpanderInputChangedEventArgs>

Remarks

Mcp23xxxx
Status
Source code	GitHub
NuGet package

The MCP chip family, referred to as MCP23XXX to represent the variations, is a digital I/O expander chip that uses I2C to communicate. It can be used to add additional digital input and output ports to Meadow and can be combined with up to eight MCP23xxx chips in total, providing 64 additional ports.

MCP23XXX chips are ubiquitous in the hardware world and is the typical interface chip for common I2C LCD backpacks, with the 74595 chip being the typical interface chip for SPI LCD backpacks.

MCP Chip Family

The MCP23XXX family includes the 8-bit MCP23008 and also includes the MCP23017, which is a 16-bit version of the MCP23008, offering 16 digital ports in total, and the MCP23S08 and MCP23S017 which are SPI versions of the MCP23008 and MCP23017, respectively.

Chip Addressing

The I2C address of the chip is configurable via the address pins and is in the binary form of 0100[A2][A1][A0], where A2, A1, and A0 refer to the three address pins on the chip:

For example, if all address pins were tied to ground, then the address of the chip would be 0100000 in binary, or 0x20 in hex, and 32 in decimal.

The I2C addresses can then be as follows, where 0 represents an address pin connected to ground, and 1 represents an address pin connected to 3.3V:

Address Header	A2	A1	A0	Resulting Hex Address	Resulting Decimal Address
0100	0	0	0	0x20	32
0100	0	0	1	0x21	33
0100	0	1	0	0x22	34
0100	0	1	1	0x23	35
0100	1	0	0	0x24	36
0100	1	0	1	0x25	37
0100	1	1	0	0x26	38
0100	1	1	1	0x27	39

Because there are 8 address possibilities, it's possible to put 8 MCP23XXX chips on a single I2C bus.

To make this simpler, when instantiating one of the MCP23XXX family of chip objects, there is a constructor overload that takes the address pin configurations instead of an address, so that Meadow.Foundation uses the appropriate address based on the pins, instead of requiring a pre-computed address.

Other Pins

In addition to the address pins, there are a number of other pins that must be connected up:

• Not Reset - The RESET pin is actually a "Not Reset." The line above "Reset" means "not." So unless that pin is pulled high (3.3V), the chip will reset itself at random times and you'll get connection errors.
• SCL and SDA - The SCL and SDA pins are the I2C clock and data pins and go to the SC and SD pins on the Meadow, respectively. Each of these should also generally be pulled high (3.3V) via a 4.7kΩ resistor. See the I2C guide for more information.
• INT - The INT pin is for interrupt notifications, and is only necessary when using the GPIO pins in input mode and you want an event raised when the input value changes.
• VSS and VDD - These go to ground and 3.3V power, respectively, and power the chip.

Code Examples

You can find code examples and links to sample projects for each of the MCP23XXX families and specific chips.

• MCP23x0x
  • MCP23008
  • MCP23009
  • MCP23S08
  • MCP23S09
• MCP23x1x
  • MCP23017
  • MCP23018
  • MCP23S17
  • MCP23S18