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main.go
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main.go
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package main
import (
"github.com/ziutek/ftdi"
"log"
"time"
)
func checkErr(err error) {
if err != nil {
log.Fatal(err)
}
}
const (
baudrate = 192
Bps = baudrate * 32 // for FT323R
chunkSize = 2 * 64
bufLen = 2 * 62 // 62 because of 2 status bytes in every 64B USB packet
dt = time.Second / Bps
)
func find1(buf []byte) int {
for i, b := range buf {
if b&0x02 != 0 {
return i
}
}
return -1
}
func find0(buf []byte) int {
for i, b := range buf {
if b&0x02 == 0 {
return i
}
}
return -1
}
func twoBits(b []byte) byte {
b0 := b[0]&0x02 == 0
b1 := b[1]&0x02 == 0
if b0 && b1 {
return '.'
} else if !b0 && !b1 {
return 'O'
} else {
return 'o'
}
}
func main() {
d, err := ftdi.OpenFirst(0x0403, 0x6001, ftdi.ChannelAny)
checkErr(err)
defer d.Close()
checkErr(d.SetBitmode(0x00, ftdi.ModeReset))
checkErr(d.SetBitmode(0x01, ftdi.ModeBitbang))
checkErr(d.SetBaudrate(baudrate))
//checkErr(d.SetLatencyTimer(4))
lat, err := d.LatencyTimer()
checkErr(err)
log.Println("latency:", lat)
checkErr(d.SetReadChunkSize(chunkSize))
checkErr(d.WriteByte(0))
buf := make([]byte, bufLen)
pulseLen := 0
for {
n, err := d.Read(buf)
checkErr(err)
data := buf
if n != len(buf) {
log.Printf("Partial buffer: %d/%d", n, len(buf))
data = buf[:n]
}
show := make([]byte, len(data)/2)
for i := range show {
k := i * 2
show[i] = twoBits(data[k : k+2])
}
log.Printf("%s", show)
continue
analysis:
if pulseLen > 0 {
if i := find0(data); i != -1 {
pulseLen += i
ms := time.Duration(pulseLen) * dt / time.Millisecond
c := '?'
if ms >= 40 && ms <= 130 {
c = '0'
} else if ms >= 140 && ms <= 250 {
c = '1'
}
log.Printf("%c (%s)", c, time.Duration(pulseLen)*dt)
data = data[i+1:]
pulseLen = 0
goto analysis
} else {
pulseLen += len(data)
}
} else {
if i := find1(data); i != -1 {
data = data[i+1:]
pulseLen = 1
goto analysis
}
}
}
checkErr(d.SetBitmode(0x00, ftdi.ModeReset))
}