97 lines
1.8 KiB
Go
97 lines
1.8 KiB
Go
package beaglebone
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import (
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"fmt"
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"github.com/hybridgroup/gobot/sysfs"
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"os"
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"strings"
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)
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type pwmPin struct {
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pinNum string
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pwmDevice string
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}
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// newPwmPin creates a new pwm pin with specified pin number
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func newPwmPin(pinNum string, ocp string) (p *pwmPin, err error) {
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var fi sysfs.File
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p = &pwmPin{
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pinNum: strings.ToUpper(pinNum),
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}
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pwmDevice, err := glob(fmt.Sprintf("%v/pwm_test_%v.*", ocp, p.pinNum))
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if err != nil {
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return
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}
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p.pwmDevice = pwmDevice[0]
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for i := 0; i < 10; i++ {
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fi, err = sysfs.OpenFile(fmt.Sprintf("%v/run", p.pwmDevice), os.O_RDWR|os.O_APPEND, 0666)
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defer fi.Close()
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if err != nil && i == 9 {
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return
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} else {
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break
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}
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}
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_, err = fi.WriteString("1")
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if err != nil {
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return
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}
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err = fi.Sync()
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if err != nil {
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return
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}
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for {
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if _, err := sysfs.OpenFile(fmt.Sprintf("%v/period", p.pwmDevice), os.O_RDONLY, 0644); err == nil {
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break
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}
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}
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for {
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if _, err := sysfs.OpenFile(fmt.Sprintf("%v/duty", p.pwmDevice), os.O_RDONLY, 0644); err == nil {
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break
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}
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}
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return
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}
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// pwmWrite writes to a pwm pin with specified period and duty
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func (p *pwmPin) pwmWrite(period string, duty string) (err error) {
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f1, err := sysfs.OpenFile(fmt.Sprintf("%v/period", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
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defer f1.Close()
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if err != nil {
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return
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}
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_, err = f1.WriteString(period)
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if err != nil {
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return
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}
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f2, err := sysfs.OpenFile(fmt.Sprintf("%v/duty", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
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defer f2.Close()
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if err != nil {
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return
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}
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_, err = f2.WriteString(duty)
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if err != nil {
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return
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}
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return
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}
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// releae writes string to close a pwm pin
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func (p *pwmPin) release() (err error) {
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fi, err := sysfs.OpenFile(fmt.Sprintf("%v/run", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
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defer fi.Close()
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if err != nil {
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return
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}
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_, err = fi.WriteString("0")
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return
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}
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