package beaglebone import ( "fmt" "os" "strings" "github.com/hybridgroup/gobot/sysfs" ) type pwmPin struct { pinNum string pwmDevice string } // newPwmPin creates a new pwm pin with specified pin number func newPwmPin(pinNum string, ocp string) (p *pwmPin, err error) { var fi sysfs.File 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] for i := 0; i < 10; i++ { fi, err = sysfs.OpenFile(fmt.Sprintf("%v/run", p.pwmDevice), os.O_RDWR|os.O_APPEND, 0666) defer fi.Close() if err != nil && i == 9 { return } else { break } } _, err = fi.WriteString("1") if err != nil { return } err = fi.Sync() if err != nil { return } for { if _, err := sysfs.OpenFile(fmt.Sprintf("%v/period", p.pwmDevice), os.O_RDONLY, 0644); err == nil { break } } for { if _, err := sysfs.OpenFile(fmt.Sprintf("%v/duty", p.pwmDevice), os.O_RDONLY, 0644); err == nil { break } } 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 } _, err = f1.WriteString(period) if 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) if err != nil { return } return } // 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 }