Meadow.Foundation.Motors.HBridgeMotor

HBridgeMotor
Status
Source code	GitHub
NuGet package

An h-bridge motor controller enables a control signal to drive a much larger load in either polarity, allowing Meadow to drive DC motors in forward or reverse from an external power supply. Using pulse-width-modulation (PWM) as the control signal, provides forward or reverse control, and variable speeds in either direction.

Code Example

protected HBridgeMotor motor1;

public override Task Initialize()
{
    Resolver.Log.Info("Initializing...");

    motor1 = new HBridgeMotor
    (
        a1Port: Device.CreatePwmPort(Device.Pins.D07, new Frequency(100, Frequency.UnitType.Hertz)),
        a2Port: Device.CreatePwmPort(Device.Pins.D08, new Frequency(100, Frequency.UnitType.Hertz)),
        enablePort: Device.CreateDigitalOutputPort(Device.Pins.D09)
    );

    return Task.CompletedTask;
}

public override async Task Run()
{
    Resolver.Log.Info("TestMotor...");

    while (true)
    {
        // Motor Forwards
        motor1.Power = 1f;
        await Task.Delay(1000);

        // Motor Stops
        motor1.Power = 0f;
        await Task.Delay(500);

        // Motor Backwards
        motor1.Power = -1f;
        await Task.Delay(1000);
    }
}

Sample project(s) available on GitHub

Wiring Example

Though h-bridge motor controllers come in various form factors, they typically share the following pins and usages:

Motor Controller Pin	Description
1,2EN or ENABLE A	Motor 1 enable. This should be configured as enablePin in the constructor, and it controls whether or not the motor is powered. The HBridgeMotor driver will automatically set this to high (enabled) when the speed is not zero. This is also enabled when IsNeutral is set to false, as powering the motor will cause it to brake when the speed is set to 0. On the L2N93E and SN754410 chips, this is labeled as 1,2EN, and on the L298N, it's typically labeled as ENABLE A.
3,4EN or ENABLE B	Motor 2 enable pin. If you are driving two motors, you'll need two HBridgeMotor objects, as shown in the example below.
[1,2]A or INPUT [1,2]	Motor 1 control inputs. These are configured as the a1Pin and a2pin constructor parameter. These are the low-voltage control signals for motor 1 forward and reverse. On the L2N93E and SN754410 chips, this is labeled as 1A and 2A, and on the L298N chip, it's typically labeled as INPUT 1 and INPUT 2.
[3,4]A or INPUT [3,4]	Motor 2 control inputs.
GROUND or GND	Common/ground. Both the motor power supply and the logic power supply should be tied together on the same common ground plane.
VCC2, +12V, or Vs	This is the positive voltage supply that drives the motors. Depending on the chip used, this may be anywhere from 4.5V up to 50V.
VCC1, +5V, or VSS	This is the logic voltage supply that powers the chip logic. This should be tied into the 5V voltage pin on the Meadow.

The following breadboard diagram illustrates connecting two motors to an h-bridge chip that uses a external power supply to drive the motors:

Class HBridgeMotor

Generic h-bridge motor controller.

Assembly: Meadow.Foundation.dll

View Source

Declaration

public class HBridgeMotor : IDCMotor

Derived:
Meadow.Foundation.Motors.Tb67h420ftg.Motor

Implements:
Meadow.Peripherals.Motors.IDCMotor

Properties

IsNeutral

When true, the wheels spin "freely"

View Source

Declaration

public bool IsNeutral { get; set; }

Power

The power applied to the motor, as a percentage between -1.0 and 1.0.

View Source

Declaration

public float Power { get; set; }

PwmFrequency

The frequency of the PWM used to drive the motors. Default value is 1600.

View Source

Declaration

public Frequency PwmFrequency { get; }

MotorCalibrationMultiplier

Not all motors are created equally. This number scales the Speed Input so that you can match motor speeds without changing your logic.

View Source

Declaration

public float MotorCalibrationMultiplier { get; set; }

Fields

motorLeftPwm

PWM port for left motor

View Source

Declaration

protected IPwmPort motorLeftPwm

motorRighPwm

PWM port for right motor

View Source

Declaration

protected IPwmPort motorRighPwm

enablePort

Digital output port to enable h-bridge

View Source

Declaration

protected IDigitalOutputPort enablePort

Implements

• Meadow.Peripherals.Motors.IDCMotor