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2014-04-28 04:39:51 -07:00
package beaglebone
import (
"fmt"
"os"
"path/filepath"
"strings"
)
type pwmPin struct {
pinNum string
pwmDevice string
}
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// newPwmPin creates a new pwm pin with specified pin number
func newPwmPin(pinNum string) *pwmPin {
var err error
var fi *os.File
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d := &pwmPin{
pinNum: strings.ToUpper(pinNum),
}
ensureSlot(fmt.Sprintf("bone_pwm_%v", d.pinNum))
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ocp, err := filepath.Glob(Ocp)
if err != nil {
panic(err)
}
pwmDevice, err := filepath.Glob(fmt.Sprintf("%v/pwm_test_%v.*", ocp[0], d.pinNum))
if err != nil {
panic(err)
}
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d.pwmDevice = pwmDevice[0]
for i := 0; i < 10; i++ {
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fi, err = os.OpenFile(fmt.Sprintf("%v/run", d.pwmDevice), os.O_RDWR|os.O_APPEND, 0666)
if err != nil && i == 9 {
panic(err)
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} else {
break
}
}
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fi.WriteString("1")
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fi.Sync()
fi.Close()
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for {
if _, err := os.Stat(fmt.Sprintf("%v/period", d.pwmDevice)); err == nil {
break
}
}
for {
if _, err := os.Stat(fmt.Sprintf("%v/duty", d.pwmDevice)); err == nil {
break
}
}
return d
}
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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) {
var err error
var fi *os.File
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fi, err = os.OpenFile(fmt.Sprintf("%v/period", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
if err != nil {
panic(err)
}
fi.WriteString(period)
fi.Close()
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fi, err = os.OpenFile(fmt.Sprintf("%v/duty", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
if err != nil {
panic(err)
}
fi.WriteString(duty)
fi.Close()
}
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// releae writes string to close a pwm pin
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func (p *pwmPin) release() {
fi, err := os.OpenFile(fmt.Sprintf("%v/run", p.pwmDevice), os.O_WRONLY|os.O_APPEND, 0666)
if err != nil {
panic(err)
}
fi.WriteString("0")
fi.Close()
}