first

internal/uart/uart.go

@@ -0,0 +1,80 @@
+package uart
+
+import (
+	"bytes"
+	"io"
+	"strings"
+	"time"
+
+	"github.com/tarm/serial"
+)
+
+const (
+	BUFFERSIZE  = 4096
+	READTIMEOUT = 50 * time.Millisecond
+	IDLE        = 200 * time.Millisecond
+)
+
+type UART struct {
+	port *serial.Port
+}
+
+func New(device string, baud int) (*UART, error) {
+	c := &serial.Config{
+		Name:        device,
+		Baud:        baud,
+		ReadTimeout: READTIMEOUT,
+	}
+
+	p, err := serial.OpenPort(c)
+	if err != nil {
+		return nil, err
+	}
+
+	return &UART{port: p}, nil
+}
+
+func (u *UART) Write(cmd string) error {
+	_, err := u.port.Write([]byte(strings.TrimSpace(cmd) + "\r"))
+	return err
+}
+
+func (u *UART) ReadResponse() (string, error) {
+	buf := make([]byte, BUFFERSIZE)
+	var out bytes.Buffer
+
+	received := false
+	lastData := time.Now()
+	for {
+		n, err := u.port.Read(buf)
+
+		if err != nil && err != io.EOF && !errorsIsTimeout(err) {
+			return "", err
+		}
+
+		if n > 0 {
+			received = true
+			lastData = time.Now()
+			out.Write(buf[:n])
+		}
+
+		if received && time.Since(lastData) >= IDLE {
+			return strings.TrimSpace(out.String()), nil
+		}
+	}
+}
+
+func errorsIsTimeout(err error) bool {
+	return strings.Contains(strings.ToLower(err.Error()), "timeout")
+}
+
+func (u *UART) Exec(cmd string) (string, error) {
+	if err := u.Write(cmd); err != nil {
+		return "", err
+	}
+	return u.ReadResponse()
+}
+
+func (u *UART) Close() error {
+	return u.port.Close()
+}