pwm: update drivers with PWM to use new interface

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

l293x/l293x.go

@@ -56,49 +56,71 @@ func (d *Device) Stop() {
 	d.en.Low()
 }
 
+// PWM is the interface necessary for controlling the motor driver.
+type PWM interface {
+	Configure(config machine.PWMConfig) error
+	Channel(pin machine.Pin) (channel uint8, err error)
+	Top() uint32
+	Set(channel uint8, value uint32)
+	SetPeriod(period uint64) error
+}
+
 // 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
+	spc    uint8
+	pwm    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 {
+// NewWithSpeed returns a new PWMMotor driver that uses an already configured PWM channel
+// to control speed.
+func NewWithSpeed(direction1, direction2 machine.Pin, spc uint8, pwm PWM) PWMDevice {
 	return PWMDevice{
-		a1: direction1,
-		a2: direction2,
-		en: speedPin,
+		a1:  direction1,
+		a2:  direction2,
+		spc: spc,
+		pwm: pwm,
 	}
 }
 
-// Configure configures the PWMDevice.
-func (d *PWMDevice) Configure() {
+// Configure configures the PWMDevice. Note that the PWM interface and
+// channel must already be configured, this function will not do it for you.
+func (d *PWMDevice) Configure() error {
 	d.a1.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	d.a2.Configure(machine.PinConfig{Mode: machine.PinOutput})
-	d.en.Configure()
 
 	d.Stop()
+
+	return nil
 }
 
-// Forward turns motor on in forward direction at specific speed.
-func (d *PWMDevice) Forward(speed uint16) {
+// Forward turns motor on in forward direction at specific speed as a percentage.
+func (d *PWMDevice) Forward(speed uint32) {
+	if speed > 100 {
+		speed = 100
+	}
+
 	d.a1.High()
 	d.a2.Low()
-	d.en.Set(speed)
+	d.pwm.Set(d.spc, d.pwm.Top()*speed/100)
 }
 
-// Backward turns motor on in backward direction at specific speed.
-func (d *PWMDevice) Backward(speed uint16) {
+// Backward turns motor on in backward direction at specific speed as a percentage.
+func (d *PWMDevice) Backward(speed uint32) {
+	if speed > 100 {
+		speed = 100
+	}
+
 	d.a1.Low()
 	d.a2.High()
-	d.en.Set(speed)
+	d.pwm.Set(d.spc, d.pwm.Top()*speed/100)
 }
 
 // Stop turns motor off.
 func (d *PWMDevice) Stop() {
 	d.a1.Low()
 	d.a2.Low()
-	d.en.Set(0)
+	d.pwm.Set(d.spc, 0)
 }