Merge pull request #594 from starryalley/master

raspi: export PiBlasterPeriod in Adaptor

platforms/raspi/pwm_pin.go

@@ -9,13 +9,12 @@ import (
 	"gobot.io/x/gobot/sysfs"
 )
 
-const piBlasterPeriod = 10000000
-
 // PWMPin is the Raspberry Pi implementation of the PWMPinner interface.
 // It uses Pi Blaster.
 type PWMPin struct {
 	pin    string
 	dc     uint32
+	period uint32
 }
 
 // NewPwmPin returns a new PWMPin
@@ -51,11 +50,19 @@ func (p *PWMPin) InvertPolarity(invert bool) (err error) {
 
 // Period returns the current PWM period for pin
 func (p *PWMPin) Period() (period uint32, err error) {
-	return piBlasterPeriod, nil
+	if p.period == 0 {
+		return p.period, errors.New("Raspi PWM pin period not set")
 	}
 
-// SetPeriod does not do anything when using PiBlaster
+	return p.period, nil
+}
+
+// SetPeriod uses PiBlaster setting and cannot be changed once set
 func (p *PWMPin) SetPeriod(period uint32) (err error) {
+	if p.period != 0 {
+		return errors.New("Cannot set the period of individual PWM pins on Raspi")
+	}
+	p.period = period
 	return nil
 }
 
@@ -66,12 +73,16 @@ func (p *PWMPin) DutyCycle() (duty uint32, err error) {
 
 // SetDutyCycle writes the duty cycle to the pin
 func (p *PWMPin) SetDutyCycle(duty uint32) (err error) {
-	if duty > piBlasterPeriod {
+	if p.period == 0 {
+		return errors.New("Raspi PWM pin period not set")
+	}
+
+	if duty > p.period {
 		return errors.New("Duty cycle exceeds period.")
 	}
 	p.dc = duty
 
-	val := gobot.FromScale(float64(p.dc), 0, piBlasterPeriod)
+	val := gobot.FromScale(float64(p.dc), 0, float64(p.period))
 
 	// never go below minimum allowed duty for pi blaster
 	if val < 0.05 {

platforms/raspi/pwm_pin_test.go

@@ -20,11 +20,14 @@ func TestPwmPin(t *testing.T) {
 	val, _ = pin.Polarity()
 	gobottest.Assert(t, val, "normal")
 
-	period, _ := pin.Period()
+	period, err := pin.Period()
-	gobottest.Assert(t, period, uint32(10000000))
+	gobottest.Assert(t, err, errors.New("Raspi PWM pin period not set"))
-	gobottest.Assert(t, pin.SetPeriod(1000), nil)
+	gobottest.Assert(t, pin.SetDutyCycle(10000), errors.New("Raspi PWM pin period not set"))
+
+	gobottest.Assert(t, pin.SetPeriod(20000000), nil)
 	period, _ = pin.Period()
-	gobottest.Assert(t, period, uint32(10000000))
+	gobottest.Assert(t, period, uint32(20000000))
+	gobottest.Assert(t, pin.SetPeriod(10000000), errors.New("Cannot set the period of individual PWM pins on Raspi"))
 
 	dc, _ := pin.DutyCycle()
 	gobottest.Assert(t, dc, uint32(0))

platforms/raspi/raspi_adaptor.go

@@ -34,6 +34,7 @@ type Adaptor struct {
 	spiDevices         [2]spi.Connection
 	spiDefaultMode     int
 	spiDefaultMaxSpeed int64
+	PiBlasterPeriod    uint32
 }
 
 // NewAdaptor creates a Raspi Adaptor
@@ -43,6 +44,7 @@ func NewAdaptor() *Adaptor {
 		name:            gobot.DefaultName("RaspberryPi"),
 		digitalPins:     make(map[int]*sysfs.DigitalPin),
 		pwmPins:         make(map[int]*PWMPin),
+		PiBlasterPeriod: 10000000,
 	}
 	content, _ := readFile()
 	for _, v := range strings.Split(string(content), "\n") {
@@ -261,6 +263,7 @@ func (r *Adaptor) PWMPin(pin string) (raspiPWMPin sysfs.PWMPinner, err error) {
 
 	if r.pwmPins[i] == nil {
 		r.pwmPins[i] = NewPWMPin(strconv.Itoa(i))
+		r.pwmPins[i].SetPeriod(r.PiBlasterPeriod)
 	}
 
 	return r.pwmPins[i], nil
@@ -273,7 +276,7 @@ func (r *Adaptor) PwmWrite(pin string, val byte) (err error) {
 		return err
 	}
 
-	duty := uint32(gobot.FromScale(float64(val), 0, 255) * piBlasterPeriod)
+	duty := uint32(gobot.FromScale(float64(val), 0, 255) * float64(r.PiBlasterPeriod))
 	return sysfsPin.SetDutyCycle(duty)
 }
 
@@ -284,7 +287,7 @@ func (r *Adaptor) ServoWrite(pin string, angle byte) (err error) {
 		return err
 	}
 
-	duty := uint32(gobot.FromScale(float64(angle), 0, 180) * piBlasterPeriod)
+	duty := uint32(gobot.FromScale(float64(angle), 0, 180) * float64(r.PiBlasterPeriod))
 	return sysfsPin.SetDutyCycle(duty)
 }
 

platforms/raspi/raspi_adaptor_test.go

@@ -110,6 +110,7 @@ func TestAdaptorFinalize(t *testing.T) {
 
 func TestAdaptorDigitalPWM(t *testing.T) {
 	a := initTestAdaptor()
+	a.PiBlasterPeriod = 20000000
 
 	gobottest.Assert(t, a.PwmWrite("7", 4), nil)
 
@@ -118,6 +119,10 @@ func TestAdaptorDigitalPWM(t *testing.T) {
 	})
 	sysfs.SetFilesystem(fs)
 
+	pin, _ := a.PWMPin("7")
+	period, _ := pin.Period()
+	gobottest.Assert(t, period, uint32(20000000))
+
 	gobottest.Assert(t, a.PwmWrite("7", 255), nil)
 
 	gobottest.Assert(t, strings.Split(fs.Files["/dev/pi-blaster"].Contents, "\n")[0], "4=1")
@@ -128,6 +133,14 @@ func TestAdaptorDigitalPWM(t *testing.T) {
 
 	gobottest.Assert(t, a.PwmWrite("notexist", 1), errors.New("Not a valid pin"))
 	gobottest.Assert(t, a.ServoWrite("notexist", 1), errors.New("Not a valid pin"))
+
+	pin, _ = a.PWMPin("12")
+	period, _ = pin.Period()
+	gobottest.Assert(t, period, uint32(20000000))
+
+	gobottest.Assert(t, pin.SetDutyCycle(1.5*1000*1000), nil)
+
+	gobottest.Assert(t, strings.Split(fs.Files["/dev/pi-blaster"].Contents, "\n")[0], "18=0.075")
 }
 
 func TestAdaptorDigitalIO(t *testing.T) {