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embd/controller/servoblaster/servoblaster.go
2014-04-02 17:25:28 +05:30

68 lines
1.5 KiB
Go

// Package servoblaster allows interfacing with the software servoblaster driver.
//
// More details on ServoBlaster at: https://github.com/richardghirst/PiBits/tree/master/ServoBlaster
package servoblaster
import (
"fmt"
"os"
"github.com/golang/glog"
)
// ServoBlaster represents a software RPi PWM/PCM based servo control module.
type ServoBlaster struct {
initialized bool
fd *os.File
}
// New creates a new ServoBlaster instance.
func New() *ServoBlaster {
return &ServoBlaster{}
}
func (d *ServoBlaster) setup() error {
if d.initialized {
return nil
}
var err error
if d.fd, err = os.OpenFile("/dev/servoblaster", os.O_WRONLY, os.ModeExclusive); err != nil {
return err
}
d.initialized = true
return nil
}
type pwmChannel struct {
d *ServoBlaster
channel int
}
func (p *pwmChannel) SetMicroseconds(us int) error {
return p.d.setMicroseconds(p.channel, us)
}
func (d *ServoBlaster) Channel(channel int) *pwmChannel {
return &pwmChannel{d: d, channel: channel}
}
// SetMicroseconds sends a command to the PWM driver to generate a us wide pulse.
func (d *ServoBlaster) setMicroseconds(channel, us int) error {
if err := d.setup(); err != nil {
return err
}
cmd := fmt.Sprintf("%v=%vus\n", channel, us)
glog.V(1).Infof("servoblaster: sending command %q", cmd)
_, err := d.fd.WriteString(cmd)
return err
}
// Close closes the open driver handle.
func (d *ServoBlaster) Close() error {
if d.fd != nil {
return d.fd.Close()
}
return nil
}