Below are brief Python scripts that showcase essential functions of the Raspberry Pi Pico microcontroller. These devices assume that one or multiple I2C (or I2C) devices are connected externally. The I2C bus is a two-wire bidirectional serial bus used for short-distance low-bandwidth communication between a microcontroller and peripheral devices.
To execute any sample, just copy the program to code.py in the CIRCUITRY drive available on the board. The text can be copied from this webpage or downloaded from the CircuitPython sample code folder on this site.
I2C Bus Scan
The following utility script uses the built-in scanning feature to detect devices on the I2C bus. It uses only built-in firmware modules.
Direct download: bus_scan.py.
# bus_scan.py
# Raspberry Pi Pico - I2C Bus Scan
# Search for devices on an I2C bus.
#---- electrical connections ---------------------------------------------------
# The Pico has two hardware I2C ports which can each be mapped to a number of
# possible pin pairs. This example uses pins 6 and 7 for I2C0 SDA
# and SCL. For alternate choices please see the official pinout diagram.
# Pico description
# pin 7/GP5/I2C0 SCL I2C clock from port 0
# pin 6/GP4/I2C0 SDA I2C data from port 0
# pin 38/GND common ground
#-------------------------------------------------------------------------------
# related CircuitPython module documentation:
# busio https://circuitpython.readthedocs.io/en/latest/shared-bindings/busio/index.html
# time https://circuitpython.readthedocs.io/en/latest/shared-bindings/time/index.html
# board https://circuitpython.readthedocs.io/en/latest/shared-bindings/board/index.html
#-------------------------------------------------------------------------------
# load standard Python modules
import time
# load the CircuitPython hardware definition module for pin definitions
import board
# load the CircuitPython I2C support
import busio
#---------------------------------------------------------------
# The device is connected to I2C0 on pins 6 and 7.
i2c = busio.I2C(scl=board.GP5, sda=board.GP4)
#---------------------------------------------------------------
# Scan for devices.
if i2c.try_lock():
print("Starting I2C scan.")
devices = i2c.scan()
i2c.unlock()
print("Found %d I2C device(s)." % (len(devices)))
for dev in devices:
print(" I2C address: %d (0x%x)" % (dev, dev))
else:
print("Unable to lock I2C interface.")
Library Installation
The Pico firmware contains essential modules for utilizing the built-in I/O functions, while various additional packages are offered to assist specific hardware components. The most convenient method to set up these is by downloading a package of precompiled libraries and transferring specific packages or modules to the CIRCUITPY filesystem as required.
The version of the bundle must be the same as the version of CircuitPython that is installed. You can find the latest bundles at https://circuitpython.org/libraries. The package is a compressed file with numerous .mpy library files and example code. You’ll need to unbox it on your desktop or laptop and only install a portion of the files.
The seven-segment demo utilizes the adafruit_ht16k33 package, which consists of multiple separate modules within a folder. Unzip the library and find the adafruit_ht16k33 folder within the lib directory to install. This needs to be pasted into the lib directory of the CIRCUITPY device. This directory is included in the standard search path for importing.
To check the result, when installed correctly the Pico CIRCUITPY filesystem should include the following: lib/adafruit_ht16k33/segments.mpy
Seven-Segment LED Display
This demo shows numbers on a four-digit LED display connected via the Pico I2C bus. Please note it uses an optional library which must be installed separately.
The display is an Adafruit product: 0.56” 4-Digit 7-Segment Display w/I2C Backpack. Adafruit has a useful tutorial which describes this and several related products.
Direct download: seven_segment_demo.py.
# seven_segment_demo.py
# Raspberry Pi Pico - Seven Segment I2C Display demo
# Display a number on a four-digit seven-segment display using an I2C interface.
# This uses a particular product from Adafruit:
# Adafruit 0.56" 4-Digit 7-Segment Display w/I2C Backpack
# shop: https://www.adafruit.com/products/881 (blue version)
# tutorial: https://learn.adafruit.com/adafruit-led-backpack/0-dot-56-seven-segment-backpack
# IDeATe stocks a small quantity of these devices in Lending for long-term loan.
# The description can be found in the Physical Computing lab database under part
# numbers 2342, 2343, 2345, 2347, and 2349, corresponding to different digit
# colors.
# The board is based on a HT16K33 I2C LED driver chip. The default address
# (with no jumpers installed) is 0x70.
#---- Adafruit library ----------------------------------------------------
# This sample uses an Adafruit library which is not included in the firmware,
# but which must be copied to the board. All of these optional libraries are
# distributed in a bundle which must match the CircuitPython firmware version.
# To install, unzip the bundle zip and locate the lib/adafruit_ht16k33 folder.
# This contains several precompiled .mpy files; the folder should be copied to the
# lib folder on the CIRCUITPY device.
#
# E.g., the installed files should include the following:
# CIRCUITPY/lib/adafruit_ht16k33/segments.mpy
#---- electrical connections ---------------------------------------------------
# The Pico has two hardware I2C ports which can each be mapped to a number of
# possible pin pairs. This example uses pins 6 and 7 for I2C0 SDA
# and SCL. For alternate choices please see the official pinout diagram.
# Pico display description
# pin 7/GP5/I2C0 SCL SCL I2C clock from port 0
# pin 6/GP4/I2C0 SDA SDA I2C data from port 0
# pin 36/3.3VOUT VCC 3.3V to power display
# pin 38/GND GND common ground
################################################################
# related CircuitPython module documentation:
# busio https://circuitpython.readthedocs.io/en/latest/shared-bindings/busio/index.html
# time https://circuitpython.readthedocs.io/en/latest/shared-bindings/time/index.html
# board https://circuitpython.readthedocs.io/en/latest/shared-bindings/board/index.html
# adafruit_ht16k33 https://circuitpython.readthedocs.io/projects/ht16k33/en/latest/api.html
# Adafruit_CircuitPython_HT16K33 source: https://github.com/adafruit/Adafruit_CircuitPython_HT16K33
################################################################################
# load standard Python modules
import time
# load the CircuitPython hardware definition module for pin definitions
import board
# load the CircuitPython I2C support
import busio
# load the Adafruit HT16K33 library
import adafruit_ht16k33.segments
#---------------------------------------------------------------
# The device is connected to I2C0 on pins 6 and 7.
i2c = busio.I2C(scl=board.GP5, sda=board.GP4)
display = adafruit_ht16k33.segments.Seg7x4(i2c)
#---------------------------------------------------------------
# Run the main loop to generate a counting display.
while True:
for count in range(10000):
display.print("%04d" % count)
print("%04d" % count)
time.sleep(1)
LCD 20×4 Character Display
This demonstration presents text and numbers on a 20×4 LCD that is connected through the Pico I2C bus. Please be aware that it requires an additional library that needs to be installed on its own.
Direct download: lcd_display_demo.py.
# lcd_display_demo.py
# Raspberry Pi Pico - LCD I2C 20x4 Character Display demo
# Display text on a 20x4 character display using an I2C interface.
# IDeATe stocks a small quantity of these devices in the Hunt A10 Physical
# Computing Lab as part 0627.
# This is a generic display part which uses a PCF8574 "Remote 8-Bit I/O Expander
# for I2C Bus" to drive the LCD display parallel port. The default I2C address
# is 0x27 as determined by a bus scan.
#---- LCD library ---------------------------------------------------------
# This sample uses a third-party library which is not included in the firmware,
# but which must be copied to the board.
#
# PCF8574 LCD library: https://github.com/dhalbert/CircuitPython_LCD
#
# To install, clone the repo or download it, then copy the lcd/ folder
# to the lib/ folder on the CIRCUITPY device.
#---- electrical connections ---------------------------------------------------
# The Pico has two hardware I2C ports which can each be mapped to a number of
# possible pin pairs. This example uses pins 6 and 7 for I2C0 SDA
# and SCL. For alternate choices please see the official pinout diagram.
# Pico display description
# pin 7/GP5/I2C0 SCL SCL I2C clock from port 0
# pin 6/GP4/I2C0 SDA SDA I2C data from port 0
# pin 36/3.3VOUT VCC 3.3V to power display
# pin 38/GND GND common ground
# On the display, install a jumper on the two-pin header labeled LED in order to
# power the backlight, otherwise the display is almost unreadable.
################################################################
# related CircuitPython module documentation:
# board https://circuitpython.readthedocs.io/en/latest/shared-bindings/board/index.html
# busio https://circuitpython.readthedocs.io/en/latest/shared-bindings/busio/index.html
# time https://circuitpython.readthedocs.io/en/latest/shared-bindings/time/index.html
################################################################################
# load standard Python modules
import time
# load the CircuitPython hardware definition module for pin definitions
import board
# load the CircuitPython I2C support
import busio
# load the LCD library
import lcd.lcd
import lcd.i2c_pcf8574_interface
#---------------------------------------------------------------
# The device is connected to I2C0 on pins 6 and 7.
i2c = busio.I2C(scl=board.GP5, sda=board.GP4)
iface = lcd.i2c_pcf8574_interface.I2CPCF8574Interface(i2c, 0x27)
display = lcd.lcd.LCD(iface, num_rows=4, num_cols=20)
display.set_backlight(True)
display.set_display_enabled(True)
display.print("Hello, world.")
#---------------------------------------------------------------
# Run the main loop to generate a counting display.
while True:
for count in range(10000):
display.set_cursor_pos(1, 4)
display.print("%04d" % count)
print("%04d" % count)
time.sleep(1)
Source: I2C Examples – Raspberry Pi Pico
