import serial
import time

ser = serial.Serial('COM4', 9600)

def read_data():
    reading = str(ser.readline())
    print("Dados lido:", reading[2:][:-5])

def write_data(data):
    ser.write(data)

data_to_write = 0
while True:
    print("Enviando: ", data_to_write)
    write_data(data_to_write)
    data_to_write = int(not data_to_write)
    time.sleep(0.4)
    print("Lendo...")
    read_data()