Logging / Debugging

Every module of this package uses the Python Logging Facility to log debug messages, warnings etc when run on a Single Board Computer (SBC). It uses the adafruit_logging library for CircuitPython when run on embedded hardware, which is a CPython compatible alternative. This page gives a quick overview how the logging works.

Usage

To enable the logging facility in your project, just add the following lines to the top of your main Python script:

import logging
logging.basicConfig()

Log Raw Transmitted/Received Data

When debugging issues on a lower layer, it might be useful to see what data (raw bytes) is actually sent to the underlying transceiver, and what data is received from the connected devices. This data can be shown by changing the logging level to DEBUG:

from circuitpython_sensirion_i2c_driver import LinuxI2cTransceiver, I2cConnection, \
    I2cDevice, I2cCommand

import logging
logging.basicConfig(level=logging.DEBUG)  # <- logging level set here

with LinuxI2cTransceiver('/dev/i2c-1') as transceiver:
    device = I2cDevice(I2cConnection(transceiver), slave_address=0x69)
    response = device.execute(I2cCommand(tx_data=b"\x80\x04", rx_length=6,
                                         read_delay=5e-3, timeout=0))
    print("Received {} bytes".format(len(response)))

This way the raw data is printed to the console:

DEBUG:circuitpython_sensirion_i2c_driver.connection:I2cConnection send raw: slave_address=105 rx_length=6 read_delay=0.005 timeout=0.0 tx_data=[0x80, 0x04]
DEBUG:circuitpython_sensirion_i2c_driver.connection:I2cConnection received raw: [0x00, 0x09, 0x09, 0x3A, 0x80, 0xA7]
Received 6 bytes

Change Logging Verbosity of Modules

Since every module contains its own logging object log, it’s even possible to set the logging level of each module independently. For example, the verbosity of the I2cConnection class could be reduced by changing its logging level to CRITICAL (i.e. only critical messages will be logged):

import circuitpython_sensirion_i2c_driver
from circuitpython_sensirion_i2c_driver import LinuxI2cTransceiver, I2cConnection, \
    I2cDevice, I2cCommand

import logging
logging.basicConfig(level=logging.DEBUG)

# Make connection less verbose
circuitpython_sensirion_i2c_driver.connection.log.setLevel(level=logging.CRITICAL)

# or, assuming import board
# with CircuitPythonI2cTransceiver(board.I2C()) as transceiver:
with LinuxI2cTransceiver('/dev/i2c-1') as transceiver:
    device = I2cDevice(I2cConnection(transceiver), slave_address=0x69)
    response = device.execute(I2cCommand(tx_data=b"\x80\x04", rx_length=6,
                                         read_delay=5e-3, timeout=0))
    print("Received {} bytes".format(len(response)))

This way you won’t see the raw transmitted data:

Received 6 bytes