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raspi: add implementation for PWMPinner interface that wraps pi blaster 

Signed-off-by: deadprogram <ron@hybridgroup.com>
This commit is contained in:
deadprogram 2017-05-01 08:37:14 +02:00
parent c9ec619219
commit efb9f7647d
4 changed files with 152 additions and 23 deletions
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93
platforms/raspi/pwm_pin.go Normal file
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@ -0,0 +1,93 @@
package raspi
import (
"errors"
"fmt"
"os"
"gobot.io/x/gobot"
"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
}
// NewPwmPin returns a new PWMPin
func NewPWMPin(pin string) *PWMPin {
return &PWMPin{
pin: pin}
}
// Export exports the pin for use by the Raspberry Pi
func (p *PWMPin) Export() error {
return nil
}
// Unexport unexports the pin and releases the pin from the operating system
func (p *PWMPin) Unexport() error {
return p.piBlaster(fmt.Sprintf("release %v\n", p.pin))
}
// Enable enables/disables the PWM pin
func (p *PWMPin) Enable(e bool) (err error) {
return nil
}
// Polarity returns the polarity either normal or inverted
func (p *PWMPin) Polarity() (polarity string, err error) {
return "normal", nil
}
// InvertPolarity does not do anything when using PiBlaster
func (p *PWMPin) InvertPolarity(invert bool) (err error) {
return nil
}
// Period returns the current PWM period for pin
func (p *PWMPin) Period() (period uint32, err error) {
return piBlasterPeriod, nil
}
// SetPeriod does not do anything when using PiBlaster
func (p *PWMPin) SetPeriod(period uint32) (err error) {
return nil
}
// DutyCycle returns the duty cycle for the pin
func (p *PWMPin) DutyCycle() (duty uint32, err error) {
return p.dc, nil
}
// SetDutyCycle writes the duty cycle to the pin
func (p *PWMPin) SetDutyCycle(duty uint32) (err error) {
if duty > piBlasterPeriod {
return errors.New("Duty cycle exceeds period.")
}
p.dc = duty
val := gobot.FromScale(float64(p.dc), 0, piBlasterPeriod)
// never go below minimum allowed duty for pi blaster
if val < 0.05 {
val = 0.05
}
return p.piBlaster(fmt.Sprintf("%v=%v\n", p.pin, val))
}
func (p *PWMPin) piBlaster(data string) (err error) {
fi, err := sysfs.OpenFile("/dev/pi-blaster", os.O_WRONLY|os.O_APPEND, 0644)
defer fi.Close()
if err != nil {
return err
}
_, err = fi.WriteString(data)
return
}

38
platforms/raspi/pwm_pin_test.go Normal file
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@ -0,0 +1,38 @@
package raspi
import (
"testing"
"gobot.io/x/gobot/gobottest"
"gobot.io/x/gobot/sysfs"
)
var _ sysfs.PWMPinner = (*PWMPin)(nil)
func TestPwmPin(t *testing.T) {
pin := NewPWMPin("1")
gobottest.Assert(t, pin.Export(), nil)
gobottest.Assert(t, pin.Enable(true), nil)
val, _ := pin.Polarity()
gobottest.Assert(t, val, "normal")
gobottest.Assert(t, pin.InvertPolarity(true), nil)
val, _ = pin.Polarity()
gobottest.Assert(t, val, "normal")
period, _ := pin.Period()
gobottest.Assert(t, period, uint32(10000000))
gobottest.Assert(t, pin.SetPeriod(1000), nil)
period, _ = pin.Period()
gobottest.Assert(t, period, uint32(10000000))
dc, _ := pin.DutyCycle()
gobottest.Assert(t, dc, uint32(0))
// call currently fails in test
gobottest.Refute(t, pin.SetDutyCycle(10000), nil)
dc, _ = pin.DutyCycle()
gobottest.Assert(t, dc, uint32(10000))
// call currently fails in test
gobottest.Refute(t, pin.Unexport(), nil)
}

38
platforms/raspi/raspi_adaptor.go
View File

@ -23,7 +23,7 @@ type Adaptor struct {
name string
revision string
digitalPins map[int]*sysfs.DigitalPin
pwmPins []int
pwmPins map[int]*PWMPin
i2cDefaultBus int
i2cBuses [2]sysfs.I2cDevice
}
@ -33,7 +33,7 @@ func NewAdaptor() *Adaptor {
r := &Adaptor{
name: gobot.DefaultName("RaspberryPi"),
digitalPins: make(map[int]*sysfs.DigitalPin),
pwmPins: []int{},
pwmPins: make(map[int]*PWMPin),
}
content, _ := readFile()
for _, v := range strings.Split(string(content), "\n") {
@ -77,10 +77,12 @@ func (r *Adaptor) Finalize() (err error) {
}
}
for _, pin := range r.pwmPins {
if perr := r.piBlaster(fmt.Sprintf("release %v\n", pin)); err != nil {
if pin != nil {
if perr := pin.Unexport(); err != nil {
err = multierror.Append(err, perr)
}
}
}
for _, bus := range r.i2cBuses {
if bus != nil {
if e := bus.Close(); e != nil {
@ -150,23 +152,24 @@ func (r *Adaptor) GetDefaultBus() int {
// PwmWrite writes a PWM signal to the specified pin
func (r *Adaptor) PwmWrite(pin string, val byte) (err error) {
sysfsPin, err := r.pwmPin(pin)
sysfsPin, err := r.PWMPin(pin)
if err != nil {
return err
}
return r.piBlaster(fmt.Sprintf("%v=%v\n", sysfsPin, gobot.FromScale(float64(val), 0, 255)))
duty := uint32(gobot.FromScale(float64(val), 0, 255) * piBlasterPeriod)
return sysfsPin.SetDutyCycle(duty)
}
// ServoWrite writes a servo signal to the specified pin
func (r *Adaptor) ServoWrite(pin string, angle byte) (err error) {
sysfsPin, err := r.pwmPin(pin)
sysfsPin, err := r.PWMPin(pin)
if err != nil {
return err
}
val := (gobot.ToScale(gobot.FromScale(float64(angle), 0, 180), 0, 200) / 1000.0) + 0.05
return r.piBlaster(fmt.Sprintf("%v=%v\n", sysfsPin, val))
duty := uint32(gobot.FromScale(float64(angle), 0, 180) * piBlasterPeriod)
return sysfsPin.SetDutyCycle(duty)
}
func (r *Adaptor) translatePin(pin string) (i int, err error) {
@ -181,25 +184,20 @@ func (r *Adaptor) translatePin(pin string) (i int, err error) {
return
}
func (r *Adaptor) pwmPin(pin string) (i int, err error) {
i, err = r.translatePin(pin)
func (r *Adaptor) PWMPin(pin string) (raspiPWMPin *PWMPin, err error) {
i, err := r.translatePin(pin)
if err != nil {
return
}
newPin := true
for _, pin := range r.pwmPins {
if i == pin {
newPin = false
if r.pwmPins[i] == nil {
r.pwmPins[i] = NewPWMPin(strconv.Itoa(i))
if err = r.pwmPins[i].Export(); err != nil {
return
}
}
if newPin {
r.pwmPins = append(r.pwmPins, i)
}
return
return r.pwmPins[i], nil
}
func (r *Adaptor) piBlaster(data string) (err error) {

4
platforms/raspi/raspi_adaptor_test.go
View File

@ -110,9 +110,9 @@ func TestAdaptorDigitalPWM(t *testing.T) {
gobottest.Assert(t, strings.Split(fs.Files["/dev/pi-blaster"].Contents, "\n")[0], "4=1")
gobottest.Assert(t, a.ServoWrite("11", 255), nil)
gobottest.Assert(t, a.ServoWrite("11", 90), nil)
gobottest.Assert(t, strings.Split(fs.Files["/dev/pi-blaster"].Contents, "\n")[0], "17=0.25")
gobottest.Assert(t, strings.Split(fs.Files["/dev/pi-blaster"].Contents, "\n")[0], "17=0.5")
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"))