Go Write Random Bytes to Serial Port

joystick-demo.go

package main

import (
      "github.com/tarm/goserial"
      "log"
      "flag"
      "math/rand"
      . "time"
)

// Command Line Args
// EX: ./joystick-demo.exe -com=COM1 -baud=115200 -readBytes=true -count=10 -delay=5
var (
  com  string
  baud int
  count int
  delay int
  readBytes = flag.Bool("readBytes", false, "Whether to read bytes in on Rx")
)

// Set Defaults
func init() {
  flag.StringVar(&com, "com", "COM4", "The COM port to write data to")
  flag.IntVar(&baud, "baud", 230400, "The Baud Rate")
  flag.IntVar(&count, "count", 20, "The Amount of times to send data")
  flag.IntVar(&delay, "delay", 3, "The Amount of delay in seconds before writing out bytes")
}

func main() {

      flag.Parse()

      // Program Info
      log.Printf("Starting with port %s at baud rate %d", com, baud)
      log.Printf("Running program %d times, delay is %d seconds", count, delay)
      log.Printf("Reading Bytes? %t", *readBytes)

      // Set Seed
      rand.Seed(Now().Unix())

      // Setup Serial Port
      c := &serial.Config{Name: com, Baud: baud}
      s, err := serial.OpenPort(c)
      if err != nil {
              log.Fatal(err)
      }

      Sleep(Duration(delay) * Second)

      // Declarations
      var start_byte, end_byte uint8

      // 0xBE
      start_byte = 190

      // 0xEF
      end_byte = 239

      buf := make([]uint8, 4)

      // Write bytes
      for i := 0; i < count; i++ {

        buf[0] = start_byte
        buf[1] = uint8(rand.Intn(255))
        buf[2] = uint8(rand.Intn(255))
        buf[3] = end_byte

        n, err := s.Write(buf)
        if err != nil {
                log.Fatal(err)
        }

        log.Printf("Wrote %d bytes", n)
        log.Print(buf[:n])

        // Random Delay
        Sleep(Millisecond * 10)
      }
      
      // Read Bytes In
      if *readBytes {

        Sleep(Millisecond * 1000)

        log.Print("Reading Bytes in...")

        buf2 := make([]uint8, 256)
        r, err := s.Read(buf2)
        if err != nil {
                log.Fatal(err)
        }

        // Print Bytes Read
        log.Print(buf2[:r])
      }
}