mirror of https://github.com/kidoman/embd
87 lines
2.5 KiB
Go
87 lines
2.5 KiB
Go
/*
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* Copyright (c) Karan Misra 2014
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
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* associated documentation files (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge, publish, distribute,
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* sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all copies or
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* substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
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* NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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// Package servoblaster allows interfacing with the software servoblaster driver.
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//
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// More details on ServoBlaster at: https://github.com/richardghirst/PiBits/tree/master/ServoBlaster
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package servoblaster
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import (
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"fmt"
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"os"
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"github.com/golang/glog"
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)
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// ServoBlaster represents a software RPi PWM/PCM based servo control module.
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type ServoBlaster struct {
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initialized bool
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fd *os.File
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}
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// New creates a new ServoBlaster instance.
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func New() *ServoBlaster {
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return &ServoBlaster{}
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}
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func (d *ServoBlaster) setup() error {
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if d.initialized {
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return nil
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}
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var err error
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if d.fd, err = os.OpenFile("/dev/servoblaster", os.O_WRONLY, os.ModeExclusive); err != nil {
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return err
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}
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d.initialized = true
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return nil
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}
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type pwmChannel struct {
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d *ServoBlaster
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channel int
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}
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func (p *pwmChannel) SetMicroseconds(us int) error {
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return p.d.setMicroseconds(p.channel, us)
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}
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func (d *ServoBlaster) Channel(channel int) *pwmChannel {
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return &pwmChannel{d: d, channel: channel}
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}
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// SetMicroseconds sends a command to the PWM driver to generate a us wide pulse.
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func (d *ServoBlaster) setMicroseconds(channel, us int) error {
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if err := d.setup(); err != nil {
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return err
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}
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cmd := fmt.Sprintf("%v=%vus\n", channel, us)
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glog.V(1).Infof("servoblaster: sending command %q", cmd)
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_, err := d.fd.WriteString(cmd)
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return err
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}
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// Close closes the open driver handle.
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func (d *ServoBlaster) Close() error {
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if d.fd != nil {
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return d.fd.Close()
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}
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return nil
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}
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