80 lines
1.9 KiB
Go
80 lines
1.9 KiB
Go
// Copyright 2017 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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package pipoint
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import (
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"fmt"
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"os"
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"gobot.io/x/gobot/sysfs"
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)
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// PwmPin represents a single pin on sysfs.
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type PwmPin struct {
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Chip int
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Pin int
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}
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func writeFile(path string, value int) (wrote int, err error) {
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file, err := sysfs.OpenFile(path, os.O_WRONLY, 0644)
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defer file.Close()
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if err != nil {
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return
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}
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return file.Write([]byte(fmt.Sprintf("%d\n", value)))
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}
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func (p *PwmPin) chip() string {
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return fmt.Sprintf("/sys/class/pwm/pwmchip%d", p.Chip)
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}
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func (p *PwmPin) attr(attr string) string {
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return fmt.Sprintf("/sys/class/pwm/pwmchip%d/pwm%d/%s", p.Chip, p.Pin, attr)
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}
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// SetEnable enables or disables the PWM output.
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func (p *PwmPin) SetEnable(val int) (err error) {
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_, err = writeFile(p.attr("enable"), val)
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return
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}
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// SetPeriod sets the PWM period in ns.
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func (p *PwmPin) SetPeriod(period int) (err error) {
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_, err = writeFile(p.attr("period"), period)
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return
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}
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// SetDuty sets the on time in ns. Should be less than the period.
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func (p *PwmPin) SetDuty(duty int) (err error) {
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_, err = writeFile(p.attr("duty_cycle"), duty)
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return
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}
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// Export exports this pin.
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func (p *PwmPin) Export() (err error) {
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path := p.chip() + "/export"
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_, err = writeFile(path, p.Pin)
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return
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}
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// UnExport removes the export for this pin.
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func (p *PwmPin) UnExport() (err error) {
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path := p.chip() + "/unexport"
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_, err = writeFile(path, p.Pin)
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return
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}
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