// newPwmPin creates a new pwm pin with specified pin number
func newPwmPin(pinNum string, ocp string) (p *pwmPin, err error) {
done := make(chan error, 0)
p = &pwmPin{
pinNum: strings.ToUpper(pinNum),
}
pwmDevice, err := glob(fmt.Sprintf("%v/pwm_test_%v.*", ocp, p.pinNum))
if err != nil {
return
}
p.pwmDevice = pwmDevice[0]
go func() {
for {
if _, err := sysfs.OpenFile(fmt.Sprintf("%v/period", p.pwmDevice), os.O_RDONLY, 0644); err == nil {
break
}
}
for {
if fi, err := sysfs.OpenFile(fmt.Sprintf("%v/duty", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0644); err == nil {
defer fi.Close()
if _, err = fi.WriteString("0"); err != nil {
done <- err
}
fi.Sync()
break
}
}
for {
if fi, err := sysfs.OpenFile(fmt.Sprintf("%v/polarity", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0644); err == nil {
defer fi.Close()
if _, err = fi.WriteString("0"); err != nil {
done <- err
}
fi.Sync()
break
}
}
for {
if fi, err := sysfs.OpenFile(fmt.Sprintf("%v/run", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0644); err == nil {
defer fi.Close()
if _, err = fi.WriteString("1"); err != nil {
done <- err
}
fi.Sync()
break
}
}
done <- nil
}()
select {
case err = <-done:
return p, err
case <-time.After(500 * time.Millisecond):
return p, errors.New("could not initialize pwm device")
}
}
func ensureSlot(slots, item string) (err error) {
fi, err := sysfs.OpenFile(slots, os.O_RDWR|os.O_APPEND, 0666)
defer fi.Close()
if err != nil {
return
}
// ensure the slot is not already written into the capemanager
// (from: https://github.com/mrmorphic/hwio/blob/master/module_bb_pwm.go#L190)
scanner := bufio.NewScanner(fi)
for scanner.Scan() {
line := scanner.Text()
if strings.Index(line, item) > 0 {
return
}
}
_, err = fi.WriteString(item)
if err != nil {
return err
}
fi.Sync()
scanner = bufio.NewScanner(fi)
for scanner.Scan() {
line := scanner.Text()
if strings.Index(line, item) > 0 {
return
}
}
return
}
func writeFile(path string, data []byte) (i int, err error) {
file, err := sysfs.OpenFile(path, os.O_WRONLY, 0644)
defer file.Close()
if err != nil {
return
}
return file.Write(data)
}
// releae writes string to close a pwm pin
func (p *pwmPin) release() (err error) {
fi, err := sysfs.OpenFile(fmt.Sprintf("%v/run", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
defer fi.Close()
if err != nil {
return
}
_, err = fi.WriteString("0")
return
}
func (r *RaspiAdaptor) 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
}
// pwmWrite writes to a pwm pin with specified period and duty
func (p *pwmPin) pwmWrite(period string, duty string) (err error) {
f1, err := sysfs.OpenFile(fmt.Sprintf("%v/period", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
defer f1.Close()
if err != nil {
return
}
if _, err = f1.WriteString(period); err != nil {
return
}
f2, err := sysfs.OpenFile(fmt.Sprintf("%v/duty", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
defer f2.Close()
if err != nil {
return
}
_, err = f2.WriteString(duty)
return
}
func readFile(path string) ([]byte, error) {
file, err := sysfs.OpenFile(path, os.O_RDONLY, 0644)
defer file.Close()
if err != nil {
return make([]byte, 0), err
}
buf := make([]byte, 200)
var i = 0
i, err = file.Read(buf)
if i == 0 {
return buf, err
}
return buf[:i], err
}
// DigitalWrite writes a digital value to specified pin.
// valid usr pin values are usr0, usr1, usr2 and usr3
func (b *BeagleboneAdaptor) DigitalWrite(pin string, val byte) (err error) {
if strings.Contains(pin, "usr") {
fi, err := sysfs.OpenFile(usrLed+pin+"/brightness", os.O_WRONLY|os.O_APPEND, 0666)
defer fi.Close()
if err != nil {
return err
}
_, err = fi.WriteString(strconv.Itoa(int(val)))
return err
}
sysfsPin, err := b.digitalPin(pin, sysfs.OUT)
if err != nil {
return err
}
return sysfsPin.Write(int(val))
}
// AnalogRead returns an analog value from specified pin
func (b *BeagleboneAdaptor) AnalogRead(pin string) (val int, err error) {
analogPin, err := b.translateAnalogPin(pin)
if err != nil {
return
}
fi, err := sysfs.OpenFile(fmt.Sprintf("%v/%v", b.helper, analogPin), os.O_RDONLY, 0644)
defer fi.Close()
if err != nil {
return
}
var buf = make([]byte, 1024)
_, err = fi.Read(buf)
if err != nil {
return
}
val, _ = strconv.Atoi(strings.Split(string(buf), "\n")[0])
return
}