goserial

serial.go

package main

import (
	"bytes"
	"encoding/binary"
	"flag"
	"fmt"
	"io"
	"log"
	"time"

	"github.com/tarm/serial"
)

func main() {
	postPtr := flag.Int("pos", 0, "position")
	namePtr := flag.String("name", "/dev/tty.usbmodem1421", "dev location")
	flag.Parse()

	c := &serial.Config{Name: *namePtr, Baud: 9600}
	s, err := serial.OpenPort(c)
	if err != nil {
		log.Fatalf("Erro opening serial port %v", err)
	}

	time.Sleep(2 * time.Second) // sleep because when a connection is made with an Arudino it reboots

	send('s', int8(*postPtr), s)
}

func send(cmd byte, val int8, s io.ReadWriteCloser) error {
	buf := new(bytes.Buffer)
	if err := binary.Write(buf, binary.LittleEndian, val); err != nil {
		return fmt.Errorf("binary.Write failed: %v", err)
	}

	for _, b := range [][]byte{[]byte{cmd}, buf.Bytes()} {
		n, err := s.Write(b)
		if err != nil {
			return err
		}

		fmt.Printf("sent %d byte(s)\n", n)
	}

	return nil
}