---

#include <Servo.h>

Servo s;
char cmd = 'S';

void setup() {
  Serial.begin(9600);
  s.attach(5);
  s.write(90);
  pinMode(8, OUTPUT); 
  pinMode(9, OUTPUT); 
  pinMode(10, OUTPUT); 
  pinMode(11, OUTPUT);
}

void loop() {
  if (Serial.available() > 0) {
    cmd = Serial.read();
  }

  if (cmd == 'F') { 
    s.write(90);  
    digitalWrite(8, HIGH);  digitalWrite(9, HIGH); 
    digitalWrite(10, LOW);  digitalWrite(11, LOW); 
  }
  else if (cmd == 'B') { 
    s.write(90);  
    digitalWrite(8, LOW);   digitalWrite(9, LOW);  
    digitalWrite(10, HIGH); digitalWrite(11, HIGH); 
  }
  else if (cmd == 'R') { 
    s.write(135); 
    digitalWrite(8, HIGH);  digitalWrite(9, HIGH); 
    digitalWrite(10, LOW);  digitalWrite(11, LOW); 
  }
  else if (cmd == 'L') { 
    s.write(45);  
    digitalWrite(8, HIGH);  digitalWrite(9, HIGH); 
    digitalWrite(10, LOW);  digitalWrite(11, LOW); 
  }
  else if (cmd == 'S') { 
    s.write(90);  
    digitalWrite(8, LOW);   digitalWrite(9, LOW);  
    digitalWrite(10, LOW);  digitalWrite(11, LOW); 
  }
}

------------------------------------------------------------------------------

import tkinter as tk
import serial

try:
    ser = serial.Serial('COM3', 9600)
except:
    ser = None

root = tk.Tk()
root.title("robot")
root.geometry("500x500")

try:
    root.iconphoto(False, tk.PhotoImage(file="icon.png"))
except:
    pass

img_u = tk.PhotoImage(file="up.png")
img_d = tk.PhotoImage(file="down.png")
img_l = tk.PhotoImage(file="left.png")
img_r = tk.PhotoImage(file="right.png")

def send_f(e):
    if ser: ser.write(b'F')

def send_b(e):
    if ser: ser.write(b'B')

def send_l(e):
    if ser: ser.write(b'L')

def send_r(e):
    if ser: ser.write(b'R')

def send_s(e):
    if ser: ser.write(b'S')

fr = tk.Frame(root)
fr.place(relx=0.5, rely=0.5, anchor=tk.CENTER)

b_f = tk.Button(fr, image=img_u, text="Вперед", compound=tk.LEFT, width=100, height=50)
b_l = tk.Button(fr, image=img_l, text="Влево",  compound=tk.LEFT, width=100, height=50)
b_r = tk.Button(fr, image=img_r, text="Вправо", compound=tk.LEFT, width=100, height=50)
b_b = tk.Button(fr, image=img_d, text="Назад",  compound=tk.LEFT, width=100, height=50)

b_f.grid(row=0, column=1, pady=10, padx=10)
b_l.grid(row=1, column=0, pady=10, padx=10)
b_r.grid(row=1, column=2, pady=10, padx=10)
b_b.grid(row=2, column=1, pady=10, padx=10)

b_f.bind("<ButtonPress-1>", send_f)
b_f.bind("<ButtonRelease-1>", send_s)

b_b.bind("<ButtonPress-1>", send_b)
b_b.bind("<ButtonRelease-1>", send_s)

b_l.bind("<ButtonPress-1>", send_l)
b_l.bind("<ButtonRelease-1>", send_s)

b_r.bind("<ButtonPress-1>", send_r)
b_r.bind("<ButtonRelease-1>", send_s)

root.mainloop()