minimal.py

# MicroPython example of reading the Tiny Code Reader from Useful Sensors on a
# Pimoroni board See https://usfl.ink/ps_dev for full documentation on the module,
# and README.md in this project for details on wiring and assembly.

import struct
import time

from pimoroni_i2c import PimoroniI2C

# The code reader has the I2C ID of hex 0c, or decimal 12.
TINY_CODE_READER_I2C_ADDRESS = 0x0C

# How long to pause between sensor polls.
TINY_CODE_READER_DELAY = 0.2

TINY_CODE_READER_LENGTH_OFFSET = 0
TINY_CODE_READER_LENGTH_FORMAT = "H"
TINY_CODE_READER_MESSAGE_OFFSET = TINY_CODE_READER_LENGTH_OFFSET + struct.calcsize(TINY_CODE_READER_LENGTH_FORMAT)
TINY_CODE_READER_MESSAGE_SIZE = 254
TINY_CODE_READER_MESSAGE_FORMAT = "B" * TINY_CODE_READER_MESSAGE_SIZE
TINY_CODE_READER_I2C_FORMAT = TINY_CODE_READER_LENGTH_FORMAT + TINY_CODE_READER_MESSAGE_FORMAT
TINY_CODE_READER_I2C_BYTE_COUNT = struct.calcsize(TINY_CODE_READER_I2C_FORMAT)

PINS_BREAKOUT_GARDEN = {"sda": 4, "scl": 5}

i2c = PimoroniI2C(**PINS_BREAKOUT_GARDEN)

# Keep looping and reading the code reader results.
while True:
    read_data = bytearray(TINY_CODE_READER_I2C_BYTE_COUNT)
    i2c.readfrom_into(TINY_CODE_READER_I2C_ADDRESS, read_data)

    message_length,  = struct.unpack_from(TINY_CODE_READER_LENGTH_FORMAT, read_data, TINY_CODE_READER_LENGTH_OFFSET)
    message_bytes = struct.unpack_from(TINY_CODE_READER_MESSAGE_FORMAT, read_data, TINY_CODE_READER_MESSAGE_OFFSET)

    if message_length > 0:
        try:
            message_string = bytearray(message_bytes[0:message_length]).decode("utf-8")
            print(message_string)
        except:
            print("Couldn't decode as UTF 8")
            pass

    time.sleep(TINY_CODE_READER_DELAY)