Remarks

CharacterDisplay
Status
Source code	GitHub
NuGet package

The CharacterDisplay class represents a multiline liquid crystal character display.

These displays are commonly found in 16x2 and 20x4 character by row configurations. Each character is represented using a grid of 5x7 pixels.

The current driver implementation uses 4 or 8 GPIO pins. It's common to find controller boards with this displays that provide I2C, SPI, or serial control. These will be supported in a future update.

Code Example

CharacterDisplay display;

public override Task Initialize()
{
    //InitGpio();
    //InitGpioWithPWM();
    //InitI2c();
    InitGrove();

    return base.Initialize();
}

void InitGpio() 
{
    Resolver.Log.Info("InitGpio...");

    display = new CharacterDisplay
    (
        device: Device,
        pinRS: Device.Pins.D10,
        pinE: Device.Pins.D09,
        pinD4: Device.Pins.D08,
        pinD5: Device.Pins.D07,
        pinD6: Device.Pins.D06,
        pinD7: Device.Pins.D05,
        rows: 4, columns: 20
    );
}

void InitGpioWithPWM()
{
    Resolver.Log.Info("InitGpioWithPWM...");

    display = new CharacterDisplay
    (
        device: Device,
        pinV0: Device.Pins.D11,
        pinRS: Device.Pins.D10,
        pinE:  Device.Pins.D09,
        pinD4: Device.Pins.D08,
        pinD5: Device.Pins.D07,
        pinD6: Device.Pins.D06,
        pinD7: Device.Pins.D05,
        rows: 4, columns: 20
    );
}

void InitI2c()
{
    Resolver.Log.Info("InitI2c...");

    display = new CharacterDisplay
    (
        i2cBus: Device.CreateI2cBus(I2cBusSpeed.Standard),
        address: (byte)I2cCharacterDisplay.Addresses.Default,
        rows: 4, columns: 20
    );
}

void InitGrove()
{
    Resolver.Log.Info("InitGrove...");

    display = new CharacterDisplay
    (
        i2cBus: Device.CreateI2cBus(I2cBusSpeed.Standard),
        address: (byte)I2cCharacterDisplay.Addresses.Grove,
        rows: 2, columns: 16,
        isGroveDisplay: true
    );
}

void TestCharacterDisplay() 
{
    Resolver.Log.Info("TestCharacterDisplay...");

    display.WriteLine("Hello", 0);

    display.WriteLine("Display", 1);

    Thread.Sleep(1000);
    display.WriteLine("Will delete in", 0);

    int count = 5;
    while(count > 0)
    {
        display.WriteLine($"{count--}", 1);
        Thread.Sleep(500);
    }

    display.ClearLines();
    Thread.Sleep(2000);

    display.WriteLine("Cursor test", 0);

    for (int i = 0; i < display.DisplayConfig.Width; i++)
    {
        display.SetCursorPosition((byte)i, 1);
        display.Write("*");
        Thread.Sleep(100);
        display.SetCursorPosition((byte)i, 1);
        display.Write(" ");
    }

    display.ClearLines();
    display.WriteLine("Complete!", 0);
}

public override Task Run()
{
    TestCharacterDisplay();

    Resolver.Log.Info("Test complete");

    return base.Run();
}

Sample project(s) available on GitHub

Wiring Example

Characteristic	Locus
Inheritance	System.Object > CharacterDisplay
Namespace	Meadow.Foundation.Displays.Lcd
Assembly	CharacterDisplay.dll

Syntax

public class CharacterDisplay : ITextDisplay

Constructors

CharacterDisplay(IDigitalOutputPort, IDigitalOutputPort, IDigitalOutputPort, IDigitalOutputPort, IDigitalOutputPort, IDigitalOutputPort, Byte, Byte)

Create a new CharacterDisplay object

Declaration

public CharacterDisplay(IDigitalOutputPort portRS, IDigitalOutputPort portE, IDigitalOutputPort portD4, IDigitalOutputPort portD5, IDigitalOutputPort portD6, IDigitalOutputPort portD7, byte rows = null, byte columns = null)

Parameters

Type	Name	Description
IDigitalOutputPort	portRS	Port for RS pin
IDigitalOutputPort	portE	Port for W pin
IDigitalOutputPort	portD4	Port for D4 pin
IDigitalOutputPort	portD5	Port for D5 pin
IDigitalOutputPort	portD6	Port for D6 pin
IDigitalOutputPort	portD7	Port for D7 pin
System.Byte	rows	Number of character rows
System.Byte	columns	Number of character columns

CharacterDisplay(II2cBus, Byte, Byte, Byte, Boolean)

Create a new CharacterDisplay object

Declaration

public CharacterDisplay(II2cBus i2cBus, byte address = null, byte rows = null, byte columns = null, bool isGroveDisplay = false)

Parameters

Type	Name	Description
II2cBus	i2cBus	The I2C bus connected to the display
System.Byte	address	The I2C address
System.Byte	rows	The number of charcter rows
System.Byte	columns	The number of character columns
System.Boolean	isGroveDisplay	True if this is a Seeed Studio Grove display (default is false)

CharacterDisplay(IMeadowDevice, IPin, IPin, IPin, IPin, IPin, IPin, IPin, Byte, Byte)

Create a new CharacterDisplay object

Declaration

public CharacterDisplay(IMeadowDevice device, IPin pinV0, IPin pinRS, IPin pinE, IPin pinD4, IPin pinD5, IPin pinD6, IPin pinD7, byte rows = null, byte columns = null)

Parameters

Type	Name	Description
IMeadowDevice	device	The device connected to the display
IPin	pinV0	V0 pin
IPin	pinRS	RS pin
IPin	pinE	W pin
IPin	pinD4	D4 pin
IPin	pinD5	D5 pin
IPin	pinD6	D6 pin
IPin	pinD7	D7 pin
System.Byte	rows	Number of character rows
System.Byte	columns	Number of character columns

CharacterDisplay(IMeadowDevice, IPin, IPin, IPin, IPin, IPin, IPin, Byte, Byte)

Create a new character display object using GPIO

Declaration

public CharacterDisplay(IMeadowDevice device, IPin pinRS, IPin pinE, IPin pinD4, IPin pinD5, IPin pinD6, IPin pinD7, byte rows = null, byte columns = null)

Parameters

Type	Name	Description
IMeadowDevice	device	The device connected to the display
IPin	pinRS	The RS pin
IPin	pinE	The E pin
IPin	pinD4	The D4 pin
IPin	pinD5	The D5 pin
IPin	pinD6	The D6 pin
IPin	pinD7	The D7 pin
System.Byte	rows	The number of character rows
System.Byte	columns	The number of character columns

CharacterDisplay(IPwmPort, IDigitalOutputPort, IDigitalOutputPort, IDigitalOutputPort, IDigitalOutputPort, IDigitalOutputPort, IDigitalOutputPort, Byte, Byte)

Create a new CharacterDisplay object

Declaration

public CharacterDisplay(IPwmPort portV0, IDigitalOutputPort portRS, IDigitalOutputPort portE, IDigitalOutputPort portD4, IDigitalOutputPort portD5, IDigitalOutputPort portD6, IDigitalOutputPort portD7, byte rows = null, byte columns = null)

Parameters

Type	Name	Description
IPwmPort	portV0	PWM port for backlight
IDigitalOutputPort	portRS	Port for RS pin
IDigitalOutputPort	portE	Port for W pin
IDigitalOutputPort	portD4	Port for D4 pin
IDigitalOutputPort	portD5	Port for D5 pin
IDigitalOutputPort	portD6	Port for D6 pin
IDigitalOutputPort	portD7	Port for D7 pin
System.Byte	rows	Number of character rows
System.Byte	columns	Number of character columns

Properties

DisplayConfig

The display configuration for text display menu

Declaration

public TextDisplayConfig DisplayConfig { get; }

Property Value

Type	Description
TextDisplayConfig

Methods

ClearLine(Byte)

Clear a line of text

Declaration

public void ClearLine(byte lineNumber)

Parameters

Type	Name	Description
System.Byte	lineNumber	The line to clear (0 indexed)

ClearLines()

Clear all lines

Declaration

public void ClearLines()

SaveCustomCharacter(Byte[], Byte)

Save a custom character to the display

Declaration

public void SaveCustomCharacter(byte[] characterMap, byte address)

Parameters

Type	Name	Description
System.Byte[]	characterMap	The character data
System.Byte	address	The display character address (0-7)

SetCursorPosition(Byte, Byte)

Set the cursor position

Declaration

public void SetCursorPosition(byte column, byte line)

Parameters

Type	Name	Description
System.Byte	column	The cursor column
System.Byte	line	The cursor line

Show()

Update the display

Declaration

public void Show()

Write(String)

Write a string to the display

Declaration

public void Write(string text)

Parameters

Type	Name	Description
System.String	text	The text to show as a string

WriteLine(String, Byte, Boolean)

Write text to a line

Declaration

public void WriteLine(string text, byte lineNumber, bool showCursor = false)

Parameters

Type	Name	Description
System.String	text	The text to dislay
System.Byte	lineNumber	The target line
System.Boolean	showCursor	If true, show the cursor