It's easy to use the TSL2561 sensor with Python and CircuitPython, and the Adafruit CircuitPython TSL2561 module.  This module allows you to easily write Python code that reads the luminosity and more from the sensor.

You can use this sensor with any CircuitPython microcontroller board or with a computer that has GPIO and Python thanks to Adafruit_Blinka, our CircuitPython-for-Python compatibility library.

CircuitPython Microcontroller Wiring

First wire up a TSL2561 to your board exactly as shown on the previous pages for Arduino using an I2C connection.  Here's an example of wiring a Feather M0 to the sensor with I2C:

  • Board 3V to sensor VIN
  • Board GND to sensor GND
  • Board SCL to sensor SCL
  • Board SDA to sensor SDA

Python Computer Wiring

Since there's dozens of Linux computers/boards you can use we will show wiring for Raspberry Pi. For other platforms, please visit the guide for CircuitPython on Linux to see whether your platform is supported

Here's the Raspberry Pi wired with I2C:

  • Pi 3V3 to sensor VIN
  • Pi GND to sensor GND
  • Pi SCL to sensor SCK
  • Pi SDA to sensor SDA

CircuitPython Installation of TSL2561 Library

Next you'll need to install the Adafruit CircuitPython TSL2561 library on your CircuitPython board.

First make sure you are running the latest version of Adafruit CircuitPython for your board.

Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle.  For example the Circuit Playground Express guide has a great page on how to install the library bundle for both express and non-express boards.

Remember for non-express boards like the Trinket M0, Gemma M0, and Feather/Metro M0 basic you'll need to manually install the necessary libraries from the bundle:

  • adafruit_tsl2561.mpy
  • adafruit_bus_device

You can also download the adafruit_tsl2561.mpy from its releases page on Github.

Before continuing make sure your board's lib folder or root filesystem has the adafruit_tsl2561.mpy, and adafruit_bus_device files and folders copied over.

Next connect to the board's serial REPL so you are at the CircuitPython >>> prompt.

Python Installation of TSL2561 Library

You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!

Once that's done, from your command line run the following command:

  • sudo pip3 install adafruit-circuitpython-tsl2561

If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!

CircuitPython and Python Usage

To demonstrate the usage of the sensor we'll initialize it and read the luminosity from the board's Python REPL.  Run the following code to import the necessary modules and initialize the I2C connection with the sensor:

import board
import busio
import adafruit_tsl2561
i2c = busio.I2C(board.SCL, board.SDA)
sensor = adafruit_tsl2561.TSL2561(i2c)

Now you're ready to read values from the sensor using any of these properties:

  • lux - The computed light lux value measured by the sensor.
  • broadband - The broadband channel value.
  • infrared - The infrared channel value.
  • luminosity - A 2-tuple of broadband and infrared channel values.
print('Lux: {}'.format(sensor.lux))
print('Broadband: {}'.format(sensor.broadband))
print('Infrared: {}'.format(sensor.infrared))
print('Luminosity: {}'.format(sensor.luminosity))

In addition there are some properties you can both read and write to change how the sensor works:

  • gain - Get and set the gain of the light sensor.  A value of 0 is low gain mode, and a value of 1 is high gain / 16x mode.
  • integration_time - Get and set the integration time of the sensor.  A value 0 is 13.7ms, 1 is 101ms, 2 is 402ms, and 3 is manual mode.
# Set high gain mode.
sensor.gain = 1
# Set 402ms integration time.
sensor.integration_time = 2

That's all there is to using the TSL2561 sensor with CircuitPython!

Here's a complete example of reading the light value every second.  Save this as a on your board and look at the output in the serial monitor:

Full Example Code

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

import time
import board
import busio
import adafruit_tsl2561

# Create the I2C bus
i2c = busio.I2C(board.SCL, board.SDA)

# Create the TSL2561 instance, passing in the I2C bus
tsl = adafruit_tsl2561.TSL2561(i2c)

# Print chip info
print("Chip ID = {}".format(tsl.chip_id))
print("Enabled = {}".format(tsl.enabled))
print("Gain = {}".format(tsl.gain))
print("Integration time = {}".format(tsl.integration_time))

print("Configuring TSL2561...")

# Enable the light sensor
tsl.enabled = True

# Set gain 0=1x, 1=16x
tsl.gain = 0

# Set integration time (0=13.7ms, 1=101ms, 2=402ms, or 3=manual)
tsl.integration_time = 1

print("Getting readings...")

# Get raw (luminosity) readings individually
broadband = tsl.broadband
infrared = tsl.infrared

# Get raw (luminosity) readings using tuple unpacking
# broadband, infrared = tsl.luminosity

# Get computed lux value (tsl.lux can return None or a float)
lux = tsl.lux

# Print results
print("Enabled = {}".format(tsl.enabled))
print("Gain = {}".format(tsl.gain))
print("Integration time = {}".format(tsl.integration_time))
print("Broadband = {}".format(broadband))
print("Infrared = {}".format(infrared))
if lux is not None:
    print("Lux = {}".format(lux))
    print("Lux value is None. Possible sensor underrange or overrange.")

# Disble the light sensor (to save power)
tsl.enabled = False

This guide was first published on Jul 29, 2012. It was last updated on May 20, 2024.

This page (Python & CircuitPython) was last updated on May 20, 2024.

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