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
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
|
package userial
import (
"math"
"os"
"time"
"golang.org/x/sys/unix"
)
type Port struct{ f *os.File }
// OpenPort opens a named serial device and return a Port data type and error
func (spops *Serial) OpenPort(path string) (*Port, error) {
f, err := os.OpenFile(path, unix.O_RDWR|unix.O_NOCTTY|unix.O_NONBLOCK, 0666)
if err != nil {
return nil, err
}
defer func() {
if err != nil && f != nil {
f.Close()
}
}()
fg := uint32(spops.baud) | uint32(spops.data) | uint32(spops.stop) | spops.cbit
switch spops.prty {
case 1:
fg |= unix.PARENB
case 2:
fg |= unix.PARENB
fg |= unix.PARODD
}
t := unix.Termios{
Cflag: fg, Iflag: spops.ibit,
Ispeed: uint32(spops.baud),
Ospeed: uint32(spops.baud),
}
t.Cc[unix.VMIN], t.Cc[unix.VTIME] = timeout(spops.tout)
if err := unix.IoctlSetTermios(
int(f.Fd()), unix.TCSETS, &t); err != nil {
return nil, err
}
if err := unix.SetNonblock(int(f.Fd()), false); err != nil {
return nil, err
}
return &Port{f: f}, err
}
// Read implement read() method for serial port
func (p *Port) Read(b []byte) (int, error) { return p.f.Read(b) }
// Write implement write() method for serial port
func (p *Port) Write(b []byte) (int, error) { return p.f.Write(b) }
// Close implement close() method for serial port
func (p *Port) Close() error { return p.f.Close() }
// Flush implement flush() method for serial port
// flushes both data received but not read, and data written but not transmitted
func (p *Port) Flush() error {
return unix.IoctlSetInt(int(p.f.Fd()), unix.TCFLSH, unix.TCIOFLUSH)
}
// Flush implement flush() method for serial port
// flushes data received but not read
func (p *Port) FlushRead() error {
return unix.IoctlSetInt(int(p.f.Fd()), unix.TCFLSH, unix.TCIFLUSH)
}
// Flush implement flush() method for serial port
// flushes data written but not transmitted
func (p *Port) FlushWrite() error {
return unix.IoctlSetInt(int(p.f.Fd()), unix.TCFLSH, unix.TCOFLUSH)
}
// SendBreak Sends Break Signal
func (p *Port) SendBreak(d time.Duration) error {
return unix.IoctlSetInt(int(p.f.Fd()), unix.TCSBRKP, int(d))
}
// Available returns how many bytes are unused in the buffer
func (p *Port) Available() (int, error) {
return unix.IoctlGetInt(int(p.f.Fd()), unix.TIOCINQ)
}
// Buffered returns the number of bytes that have been written into the current buffer
func (p *Port) Buffered() (int, error) {
return unix.IoctlGetInt(int(p.f.Fd()), unix.TIOCOUTQ)
}
// Expose serial fd to use in some special cases, ioctl etc...
func (p *Port) File() *os.File { return p.f }
func timeout(d time.Duration) (byte, byte) {
if d > 0x0 {
t := math.Min(math.Max(float64(d.Nanoseconds()/1e6/100), 0x01), 0xff)
return 0x0, byte(t)
}
return 0x1, 0x0
}
|
