quick2wire-python-api/examples/i2c-multibyte-read at 7aede7a27f87ed7662d05495d8256b4e734f71ad · romilly/quick2wire-python-api · GitHub

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#!/usr/bin/env python3

import quick2wire.i2c as i2c

address = 0x20
iodir_register = 0x00
iopol_register = 0x01
iocon_register = 0x05
gpio_register = 0x09

with i2c.I2CMaster() as bus:
    # Ensure sequential addressing mode is on
    bus.transaction(
        i2c.writing_bytes(address, iocon_register, 0b00000000))

    # Turn all pins to read mode
    bus.transaction(
        i2c.writing_bytes(address, iodir_register, 0b11111111))

    # Alternate pin polarity
    bus.transaction(
        i2c.writing_bytes(address, iopol_register, 0b10101010))

    # Read a single byte (the GPIO register)
    gpio_buf = bytearray(1)
    bus.transaction(
        i2c.writing_bytes(address, gpio_register),
        i2c.reading_into(address, gpio_buf))

    # Read two bytes, the IODIR register and, thanks to sequential
    # addressing mode, the next register, which is IOPOL
    iodir_iopol_buf = bytearray(2)
    bus.transaction(
        i2c.writing_bytes(address, iodir_register),
        i2c.reading_into(address, iodir_iopol_buf))

    print("GPIO: ", bin(gpio_buf[0])[2:])
    print("IODIR:", bin(iodir_iopol_buf[0])[2:])
    print("IOPOL:", bin(iodir_iopol_buf[1])[2:])