Raspberry Pi Pico and TSL2591 light-to-digital converter circuitpython example

In this article we connect a TSL2591 light-to-digital converter to a Raspberry Pi Pico running Circuitpython

Sensor Information

The TSL2591 is a very high sensitivity light-to-digital converter that transforms light intensity into a digital signal output capable of direct I2C interface. The device combines one broadband photodiode (visible plus infrared) and one infrared-responding photodiode on a single CMOS integrated circuit.

Two integrating ADCs convert the photodiode currents into a digital output that represents the irradiance measured on each channel.

This digital output can be input to a microprocessor where illuminance (ambient light level) in lux is derived using an empirical formula to approximate the human eye response.

The TSL2591 supports a traditional level style interrupt that remains asserted until the firmware clears it.

Features

• Highest sensitivity to 188µLux
• Patented dual-diode architecture
• 600M:1 dynamic range
• Programmable interrupt function
• UV-rejection package

Product parameters

This is the sensor I purchased, link below

Parts Required

Schematic/Connection

I used the Adafruit TSL2591 sensor

Black for GND
Red for V+
Blue for SDA
Yellow for SCL

So color coded for ease of use, this layout shows a connection to the module

rp2040 and TSL2591

Code Example

I used Thonny for development

The following is based on a library , I copied the adafruit_tsl2591.mpy library for this device to the lib folder on my Feather M0 Express – https://circuitpython.org/libraries

This is the basic example which comes with the library

[codesyntax lang=”python”]

import time
import board
import adafruit_tsl2591
import busio

# Create sensor object, communicating over the board's default I2C bus
i2c = busio.I2C(scl=board.GP1, sda=board.GP0) # uses board.SCL and board.SDA
# Initialize the sensor.
sensor = adafruit_tsl2591.TSL2591(i2c)

# You can optionally change the gain and integration time:
# sensor.gain = adafruit_tsl2591.GAIN_LOW (1x gain)
# sensor.gain = adafruit_tsl2591.GAIN_MED (25x gain, the default)
# sensor.gain = adafruit_tsl2591.GAIN_HIGH (428x gain)
# sensor.gain = adafruit_tsl2591.GAIN_MAX (9876x gain)
# sensor.integration_time = adafruit_tsl2591.INTEGRATIONTIME_100MS (100ms, default)
# sensor.integration_time = adafruit_tsl2591.INTEGRATIONTIME_200MS (200ms)
# sensor.integration_time = adafruit_tsl2591.INTEGRATIONTIME_300MS (300ms)
# sensor.integration_time = adafruit_tsl2591.INTEGRATIONTIME_400MS (400ms)
# sensor.integration_time = adafruit_tsl2591.INTEGRATIONTIME_500MS (500ms)
# sensor.integration_time = adafruit_tsl2591.INTEGRATIONTIME_600MS (600ms)

# Read the total lux, IR, and visible light levels and print it every second.
while True:
    # Read and calculate the light level in lux.
    lux = sensor.lux
    print("Total light: {0}lux".format(lux))
    # You can also read the raw infrared and visible light levels.
    # These are unsigned, the higher the number the more light of that type.
    # There are no units like lux.
    # Infrared levels range from 0-65535 (16-bit)
    infrared = sensor.infrared
    print("Infrared light: {0}".format(infrared))
    # Visible-only levels range from 0-2147483647 (32-bit)
    visible = sensor.visible
    print("Visible light: {0}".format(visible))
    # Full spectrum (visible + IR) also range from 0-2147483647 (32-bit)
    full_spectrum = sensor.full_spectrum
    print("Full spectrum (IR + visible) light: {0}".format(full_spectrum))
    time.sleep(1.0)

[/codesyntax]

Output

Here is what I saw in Thonny REPL window

Total light: 18.9704lux
Infrared light: 109
Visible light: 7143610
Full spectrum (IR + visible) light: 7143719
Total light: 19.1923lux
Infrared light: 110
Visible light: 7209148
Full spectrum (IR + visible) light: 7209258
Total light: 24.4931lux
Infrared light: 128
Visible light: 8388840
Full spectrum (IR + visible) light: 8388968
Total light: 35.3491lux
Infrared light: 160
Visible light: 10486079
Full spectrum (IR + visible) light: 10486239

Links

Datasheet