"""Program 4-4: Loopback test. Explore the readinto() function.
           Put a jumper between the GP21 pin and the GP20 pin.
"""

import time
from machine import UART, Pin

alphabets = bytearray(12)

uart1 = UART(1, baudrate = 9600, rx = Pin(21), tx = Pin(20))
m = uart1.write("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
time.sleep_ms(30)
n = uart1.readinto(alphabets, 10)
print (m, n, alphabets)
p = uart1.readinto(alphabets)
print (p, alphabets)
q = uart1.readinto(alphabets)
print (q, alphabets)