CatchExceptions4.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-

# ar - 18-05-2021

# import os
import time
# import smbus2
from smbus2 import SMBus

# Define I2C bus
DEVICE_BUS = 1

# Define device I2C slave address.
DEVICE_ADDR = 0x17

def settle():
    time.sleep(0)

# Write byte to specified I2C register address
def putByte(RA, wbyte):
    while True:
        try:
            with SMBus(DEVICE_BUS) as pbus:
                pbus.write_byte_data(DEVICE_ADDR, RA, wbyte)
            with SMBus(DEVICE_BUS) as gbus:
                rbyte = gbus.read_byte_data(DEVICE_ADDR, RA)
            if (wbyte) <= rbyte <= (wbyte):
                print("OK ", wbyte, rbyte)
                break
            else:
#            if rbyte <  max((wbyte - 2),0):
                raise ValueError
        except ValueError:
            print("Write:", wbyte, "!= Read:", rbyte, " Trying again")
        

while True:
    putByte(0x18, 180)
#    settle()
    putByte(0x18,   0)
    time.sleep(1)

# EOF