First of all, thanks for stopping by to my post. I’m an amateur python writer, I’m writing an application to send I2C Commands to via USB-RS232 (Hardware B0CFK14PVS) to my PCF8574. I’ve struggle trying to send commands to the PCF8575 though B0CFK14PVS.

The few libraries I found to do this are basically for raspberry pi who use the smbus2 & smbus libraries but I haven’t been able to find a Windows Library.

appreciate your help on this.

Please see below my code:

import serial
import time

port = "COM1"  # Change to the appropriate CH341SER COM Port
baud_rate = 115200
ser = serial.Serial(port, baud_rate)

def i2c_start():
    ser.write(b'x02')

def i2c_stop():
    ser.write(b'x03')

def i2c_write_byte(byte):
    ser.write(byte.to_bytes(1, byteorder='big'))

def i2c_write(address, data):
    i2c_start()
    i2c_write_byte(address << 1)
    for byte in data:
        i2c_write_byte(byte)
    i2c_stop()

data_to_write = [0b00000000]  # Example data
pcf8574_address = 0x20  # Change this to the address of your PCF8574 if different
i2c_write(pcf8574_address, data_to_write)
for _ in range(8):
    data_to_write[0] += 1  # Increment the first (and only) byte in the list by one
    print("Byte " + str(data_to_write))
    i2c_write(pcf8574_address, data_to_write)
    time.sleep(1)  # Wait for 1 second between each transmission
ser.close()

The following code is the one I’ve using with a RaspBerry pi, however, I need to migrate from the Raspberry Pi to a Windows:

from bin.pcf8574 import PCF8574

i2c_port = 1  # SDA = Pin 2, SCL = Pin 3
addr = 0x20  # Address for Relay card if A0=A1=A2=0
i2c = SMBus(i2c_port)
coils = PCF8575(i2c, addr)

def write_coils(vector):
    """
    Function to write all coils in relay card. Receive an integer vector with output values
    """
    try:
        for i in range(0, 8):
            if vector[i] == 1:
                vector[i] = 0
            else:
                vector[i] = 1
        vector = vector[::-1]
        coils.port = vector
    except Exception as e:
        print("Error in write_coils:", e)

while True:
    write_coils([1,0,1,0,1,0,1,0])
    time.sleep(0.5)
    write_coils([0,1,0,1,0,1,0,1])
    time.sleep(0.5)

Thanks for the help.
Francisco