l293x: added support for h-bridge motor controller

Signed-off-by: Ron Evans <ron@hybridgroup.com>

l293x/l293x.go

@@ -0,0 +1,104 @@
+// Package l293x provides a driver to the L293/L293D H-bridge chip
+// typically used to control DC motors.
+//
+// Datasheet: https://www.ti.com/lit/ds/symlink/l293d.pdf
+//
+package l293x // import "tinygo.org/x/drivers/l293x"
+
+import (
+	"machine"
+)
+
+// Device is a motor without speed control.
+// a1 and a2 are the directional pins.
+// en is the pin turns the motor on/off.
+type Device struct {
+	a1, a2 machine.Pin
+	en     machine.Pin
+}
+
+// New returns a new Motor driver for GPIO-only operation.
+func New(direction1, direction2, enablePin machine.Pin) Device {
+	return Device{
+		a1: direction1,
+		a2: direction2,
+		en: enablePin,
+	}
+}
+
+// Configure configures the Device.
+func (d *Device) Configure() {
+	d.a1.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	d.a2.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	d.en.Configure(machine.PinConfig{Mode: machine.PinOutput})
+
+	d.Stop()
+}
+
+// Forward turns motor on in forward direction.
+func (d *Device) Forward() {
+	d.a1.High()
+	d.a2.Low()
+	d.en.High()
+}
+
+// Backward turns motor on in backward direction.
+func (d *Device) Backward() {
+	d.a1.Low()
+	d.a2.High()
+	d.en.High()
+}
+
+// Stop turns motor off.
+func (d *Device) Stop() {
+	d.a1.Low()
+	d.a2.Low()
+	d.en.Low()
+}
+
+// PWMDevice is a motor with speed control.
+// a1 and a2 are the directional GPIO pins.
+// en is the PWM pin that controls the motor speed.
+type PWMDevice struct {
+	a1, a2 machine.Pin
+	en     machine.PWM
+}
+
+// NewWithSpeed returns a new PWMMotor driver that uses a PWM pin to control speed.
+func NewWithSpeed(direction1, direction2 machine.Pin, speedPin machine.PWM) PWMDevice {
+	return PWMDevice{
+		a1: direction1,
+		a2: direction2,
+		en: speedPin,
+	}
+}
+
+// Configure configures the PWMDevice.
+func (d *PWMDevice) Configure() {
+	d.a1.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	d.a2.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	d.en.Configure()
+
+	d.Stop()
+}
+
+// Forward turns motor on in forward direction at specific speed.
+func (d *PWMDevice) Forward(speed uint16) {
+	d.a1.High()
+	d.a2.Low()
+	d.en.Set(speed)
+}
+
+// Backward turns motor on in backward direction at specific speed.
+func (d *PWMDevice) Backward(speed uint16) {
+	d.a1.Low()
+	d.a2.High()
+	d.en.Set(speed)
+}
+
+// Stop turns motor off.
+func (d *PWMDevice) Stop() {
+	d.a1.Low()
+	d.a2.Low()
+	d.en.Set(0)
+}