Remarks

HBridgeMotor
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Source code GitHub
NuGet package NuGet Gallery for Meadow.Foundation

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.

Purchasing

This generic driver works with standard h-bridges ICs such as the Texas Instruments L2N93E or SN754410 chips.

It should also work with heavier duty L298N drivers.

Code Example

protected HBridgeMotor motor1;

public override Task Initialize()
{
    Console.WriteLine("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()
{
    Console.WriteLine("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:

<img src="../../API_Assets/Meadow.Foundation.Motors.HBridgeMotor/HBridgeMotor_Fritzing.svg"

Characteristic Locus
Inheritance System.Object > HBridgeMotor > Tb67h420ftg.Motor
Namespace Meadow.Foundation.Motors
Assembly Meadow.Foundation.dll

Syntax

public class HBridgeMotor : IDCMotor

Constructors

HBridgeMotor(IMeadowDevice, IPin, IPin, IPin)

Create an HBridgeMotor object

Declaration
public HBridgeMotor(IMeadowDevice device, IPin a1Pin, IPin a2Pin, IPin enablePin)

Parameters

Type Name Description
IMeadowDevice device
IPin a1Pin
IPin a2Pin
IPin enablePin

HBridgeMotor(IMeadowDevice, IPin, IPin, IPin, Frequency)

Create an HBridgeMotor object

Declaration
public HBridgeMotor(IMeadowDevice device, IPin a1Pin, IPin a2Pin, IPin enablePin, Frequency pwmFrequency)

Parameters

Type Name Description
IMeadowDevice device
IPin a1Pin
IPin a2Pin
IPin enablePin
Frequency pwmFrequency

HBridgeMotor(IPwmPort, IPwmPort, IDigitalOutputPort)

Create an HBridgeMotor object

Declaration
public HBridgeMotor(IPwmPort a1Port, IPwmPort a2Port, IDigitalOutputPort enablePort)

Parameters

Type Name Description
IPwmPort a1Port
IPwmPort a2Port
IDigitalOutputPort enablePort

HBridgeMotor(IPwmPort, IPwmPort, IDigitalOutputPort, Frequency)

Create an HBridgeMotor object

Declaration
public HBridgeMotor(IPwmPort a1Port, IPwmPort a2Port, IDigitalOutputPort enablePort, Frequency pwmFrequency)

Parameters

Type Name Description
IPwmPort a1Port
IPwmPort a2Port
IDigitalOutputPort enablePort
Frequency pwmFrequency

Fields

enablePort

Digital output port to enable h-bridge

Declaration
protected IDigitalOutputPort enablePort

Field Value

Type Description
IDigitalOutputPort

motorLeftPwm

PWM port for left motor

Declaration
protected IPwmPort motorLeftPwm

Field Value

Type Description
IPwmPort

motorRighPwm

PWM port for right motor

Declaration
protected IPwmPort motorRighPwm

Field Value

Type Description
IPwmPort

Properties

IsNeutral

When true, the wheels spin "freely"

Declaration
public bool IsNeutral { get; set; }

Property Value

Type Description
System.Boolean

MotorCalibrationMultiplier

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

Declaration
public float MotorCalibrationMultiplier { get; set; }

Property Value

Type Description
System.Single

Power

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

Declaration
public float Power { get; set; }

Property Value

Type Description
System.Single

PwmFrequency

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

Declaration
public Frequency PwmFrequency { get; }

Property Value

Type Description
Frequency