#!/usr/bin/env python3
import time
import serial

ser = serial.Serial(
   port='/dev/ttyAMA0',
   baudrate = 4800,
   parity=serial.PARITY_NONE,
   stopbits=serial.STOPBITS_ONE,
   bytesize=serial.EIGHTBITS,
   timeout=1
)
ser.write(serial.to_bytes([0x33]))  # try to_bytes
time.sleep(2)
ser.write(b'0x33')                  # try b'
time.sleep(2)
ser.write(b'0x33')
time.sleep(4)
ser.write(b'0x33')
time.sleep(4)
ser.write(b'0x33')
time.sleep(0.4)
ser.write(b'0x33')
time.sleep(0.4)

ser.close()