diff --git a/.gitignore b/.gitignore
index daf913b..b9fd1df 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,5 @@ _testmain.go
 *.exe
 *.test
 *.prof
+*.hex
+*-linux64
\ No newline at end of file
diff --git a/build.py b/build.py
new file mode 100644
index 0000000..3bc2f4b
--- /dev/null
+++ b/build.py
@@ -0,0 +1,13 @@
+#!/usr/bin/env python3
+import subprocess
+import os
+
+def build(goos, goarch, filename):
+    env = os.environ.copy()
+    env["GOOS"] = goos
+    env["GOARCH"] = goarch
+
+    subprocess.check_call(["go", "build", "-o", filename], env = env)
+
+build("windows","amd64","flysky-updater-win64.exe")
+build("linux","amd64","flysky-updater-linux64")
diff --git a/flysky_updater.go b/flysky_updater.go
new file mode 100644
index 0000000..d27d556
--- /dev/null
+++ b/flysky_updater.go
@@ -0,0 +1,226 @@
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"github.com/cheggaaa/pb"
+	"github.com/tarm/serial"
+	"gopkg.in/alecthomas/kingpin.v2"
+	"io/ioutil"
+	"time"
+)
+
+var (
+	port     = kingpin.Arg("port", "port").Required().String()
+	filename = kingpin.Arg("filename", "filename").Required().String()
+	force    = kingpin.Flag("force", "Force flash.").Short('f').Bool()
+	verbose  = kingpin.Flag("verbose", "Verbose mode.").Short('v').Bool()
+)
+
+func make_checksum(payload []byte) []byte {
+	var checksum uint16 = 0xFFFF
+	for i := 0; i < len(payload); i++ {
+		checksum -= uint16(payload[i])
+	}
+	ret := make([]byte, 2)
+	binary.LittleEndian.PutUint16(ret, checksum)
+	return ret
+}
+
+func WriteAll(s *serial.Port, raw []byte) error {
+	if *verbose {
+		fmt.Println("Write", raw[:2], raw[2:len(raw)-2], raw[len(raw)-2:])
+	}
+	n, err := s.Write(raw)
+	if err != nil {
+		return err
+	}
+	if n != len(raw) {
+		return errors.New("Didn't write all bytes.")
+	}
+	return nil
+}
+
+func WriteFrame(s *serial.Port, payload []byte) error {
+	length := make([]byte, 2)
+	binary.LittleEndian.PutUint16(length, uint16(len(payload)+4))
+	frame := append(length, payload...)
+	frame = append(frame, make_checksum(frame)...)
+	return WriteAll(s, frame)
+}
+
+func ReadAll(s *serial.Port, n int) ([]byte, error) {
+	buf := make([]byte, n)
+	bytes_read := 0
+	for bytes_read < n {
+		c, err := s.Read(buf[bytes_read:])
+		if err != nil {
+			return nil, err
+		}
+		if c == 0 {
+			return nil, errors.New("Read timeout")
+		}
+		bytes_read += c
+	}
+	return buf, nil
+}
+
+func EmptyRx(s *serial.Port) {
+	c := 1
+	buf := make([]byte, 1024)
+	for c > 0 {
+		c, _ = s.Read(buf)
+	}
+}
+
+func ReadFrame(s *serial.Port) ([]byte, error) {
+	head, err := ReadAll(s, 3)
+	if err != nil {
+		return nil, err
+	}
+	if head[0] != 0x55 {
+		return nil, errors.New("Invalid response")
+	}
+	size := int(binary.LittleEndian.Uint16(head[1:]))
+	body, err := ReadAll(s, size-3)
+	if err != nil {
+		return nil, err
+	}
+	payload := body[:len(body)-2]
+	checksum := body[len(body)-2:]
+	if *verbose {
+		fmt.Println("Read", head, payload, checksum)
+	}
+	checksum_cmp := make_checksum(append(head, payload...))
+	if !bytes.Equal(checksum, checksum_cmp) {
+		return nil, errors.New("Invalid checksum")
+	}
+	return payload, nil
+}
+
+func ping(s *serial.Port) ([]byte, error) {
+	err := WriteFrame(s, []byte{0xC0})
+	if err != nil {
+		return nil, err
+	}
+	answer, err := ReadFrame(s)
+	if err != nil {
+		return nil, err
+	}
+	if answer[0] != 0xC0 {
+		return nil, errors.New("Unexpected answer to ping")
+	}
+	return answer, nil
+}
+
+func communicate(s *serial.Port, request []byte, response []byte) error {
+	err := WriteFrame(s, request)
+	if err != nil {
+		return err
+	}
+	msg, err := ReadFrame(s)
+	if err != nil {
+		return err
+	}
+	if !bytes.Equal(msg, response) {
+		errors.New("Unexpected response: " + hex.Dump(response))
+	}
+	return nil
+}
+
+func ask_write(s *serial.Port, address int) error {
+	ask_permission := []byte{0xc2, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
+	binary.LittleEndian.PutUint16(ask_permission[1:3], uint16(address))
+	get_permission := []byte{0xc2, 0x80, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
+	binary.LittleEndian.PutUint16(get_permission[2:4], uint16(address))
+
+	return communicate(s, ask_permission, get_permission)
+}
+
+func write_chunk(s *serial.Port, address int, data []byte) error {
+	write_instruction := []byte{0xc3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01}
+	binary.LittleEndian.PutUint16(write_instruction[1:3], uint16(address))
+	write_instruction = append(write_instruction, data...)
+	write_confirmation := []byte{0xc3, 0x00, 0x00, 0x00, 0x00}
+
+	return communicate(s, write_instruction, write_confirmation)
+}
+
+func update(s *serial.Port, firmware []byte) error {
+	start_address := 0x1800
+
+	bar := pb.New(len(firmware)).SetUnits(pb.U_BYTES)
+	bar.Start()
+
+	for bytes_written := 0; bytes_written < len(firmware); bytes_written += 1024 {
+		tries := 0
+	ask:
+		err := ask_write(s, start_address+bytes_written)
+		if err != nil {
+			tries++
+			if tries <= 3 {
+				EmptyRx(s)
+				goto ask
+			}
+		}
+		for chunk := 0; chunk < 1024; chunk += 256 {
+			err = write_chunk(s, start_address+bytes_written+chunk, firmware[bytes_written+chunk:bytes_written+chunk+256])
+			if err != nil {
+				tries++
+				if tries <= 3 {
+					EmptyRx(s)
+					goto ask
+				}
+			}
+			bar.Add(256)
+		}
+	}
+
+	bar.FinishPrint("Upload completed.")
+	return nil
+}
+
+func restart(s *serial.Port) error {
+	return WriteFrame(s, []byte{0xC1, 0x00})
+}
+
+func main() {
+	kingpin.Parse()
+
+	data, err := ioutil.ReadFile(*filename)
+	if err != nil {
+		panic(err)
+	}
+
+	if (len(data) < 0x9000 || len(data) > 0xe7ff) && !*force {
+		panic(fmt.Sprintf("Unexpected firmare size: %d bytes", len(data)))
+	}
+
+	c := &serial.Config{Name: *port, Baud: 115200, ReadTimeout: time.Second * 1}
+	s, err := serial.OpenPort(c)
+	if err != nil {
+		panic(err)
+	}
+
+	_, err = ping(s)
+	if err != nil {
+		panic(err)
+	}
+
+	err = update(s, data)
+	if err != nil {
+		panic(err)
+	}
+
+	err = restart(s)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println("Success!")
+
+	s.Close()
+}