aboutsummaryrefslogtreecommitdiff
path: root/redbutton.go
blob: 75b755efc4e8f3e106f3953237581ff371e4914e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
package redbutton

import (
	"io"
	"time"
)

const PollInterval = 200 * time.Millisecond

//go:generate stringer -type=Event

type Event int

const (
	Unknown Event = iota
	Disabled
	Pressed
	Enabled
)

func Report(dev io.ReadWriter) (Event, error) {
	// leading zero disables sending of report number
	buf := []byte{0, 0, 0, 0, 0, 0, 0, 0, 2}
	if _, err := dev.Write(buf); err != nil {
		return Unknown, err
	}
	if _, err := dev.Read(buf[:8]); err != nil {
		return Unknown, err
	}
	return Event(buf[0] & 3), nil
}

func Poll(dev io.ReadWriter, d time.Duration) <-chan Event {
	if d == 0 {
		d = PollInterval
	}
	ch := make(chan Event)
	go func() {
		prev := Disabled
		tick := time.NewTicker(d)
		defer tick.Stop()
		defer close(ch)
		for range tick.C {
			ev, err := Report(dev)
			if err != nil {
				return
			}
			if ev != prev && prev != Pressed {
				ch <- ev
			}
			prev = ev
		}
	}()
	return ch
}