README.md

Raspberry Pi Pico SDK Examples

Getting started

See Getting Started with the Raspberry Pi Pico and the README in the pico-sdk for information on getting up and running.

First Examples

App	Description	Link to prebuilt UF2
hello_serial	The obligatory Hello World program for Pico (Output over serial version)
hello_usb	The obligatory Hello World program for Pico (Output over USB version)	https://rptl.io/pico-hello-usb
blink	Blink an LED on and off.	https://rptl.io/pico-blink

ADC

App	Description
hello_adc	Display the voltage from an ADC input.
joystick_display	Display a Joystick X/Y input based on two ADC inputs.
adc_console	An interactive shell for playing with the ADC. Includes example of free-running capture mode.
onboard_temperature	Display the value of the onboard temperature sensor.
microphone_adc	Read analog values from a microphone and plot the measured sound amplitude.

Clocks

App	Description
hello_48MHz	Change the system clock frequency to 48 MHz while running.
hello_gpout	Use the general purpose clock outputs (GPOUT) to drive divisions of internal clocks onto GPIO outputs.
hello_resus	Enable the clock resuscitate feature, "accidentally" stop the system clock, and show how we recover.

CMake

App	Description
build_variants	Builds two version of the same app with different configurations

DMA

App	Description
hello_dma	Use the DMA to copy data in memory.
control_blocks	Build a control block list, to program a longer sequence of DMA transfers to the UART.
channel_irq	Use an IRQ handler to reconfigure a DMA channel, in order to continuously drive data through a PIO state machine.
sniff_crc	Use the DMA engine's 'sniff' capability to calculate a CRC32 on a data buffer.

Flash

App	Description
cache_perfctr	Read and clear the cache performance counters. Show how they are affected by different types of flash reads.
nuke	Obliterate the contents of flash. An example of a NO_FLASH binary (UF2 loaded directly into SRAM and runs in-place there). A useful utility to drag and drop onto your Pico if the need arises.
program	Erase a flash sector, program one flash page, and read back the data.
xip_stream	Stream data using the XIP stream hardware, which allows data to be DMA'd in the background whilst executing code from flash.
ssi_dma	DMA directly from the flash interface (continuous SCK clocking) for maximum bulk read performance.

GPIO

App	Description
hello_7segment	Use the GPIOs to drive a seven segment LED display.
hello_gpio_irq	Register an interrupt handler to run when a GPIO is toggled.
dht_sensor	Use GPIO to bitbang the serial protocol for a DHT temperature/humidity sensor.

See also: blink, blinking an LED attached to a GPIO.

HW divider

App	Description
hello_divider	Show how to directly access the hardware integer dividers, in case AEABI injection is disabled.

I2C

App	Description
bus_scan	Scan the I2C bus for devices and display results.
bmp280_i2c	Read and convert temperature and pressure data from a BMP280 sensor, attached to an I2C bus.
lcd_1602_i2c	Display some text on a generic 16x2 character LCD display, via I2C.
lis3dh_i2c	Read acceleration and temperature value from a LIS3DH sensor via I2C
mcp9808_i2c	Read temperature, set limits and raise alerts when limits are surpassed.
mma8451_i2c	Read acceleration from a MMA8451 accelerometer and set range and precision for the data.
mpl3115a2_i2c	Interface with an MPL3115A2 altimeter, exploring interrupts and advanced board features, via I2C.
mpu6050_i2c	Read acceleration and angular rate values from a MPU6050 accelerometer/gyro, attached to an I2C bus.
ssd1306_i2c	Convert and display a bitmap on a 128x32 or 128x64 SSD1306-driven OLED display
pa1010d_i2c	Read GPS location data, parse and display data via I2C.
pcf8523_i2c	Read time and date values from a real time clock. Set current time and alarms on it.
ht16k33_i2c	Drive a 4 digit 14 segment LED with an HT16K33.
slave_mem_i2c	i2c slave example where the slave implements a 256 byte memory

Interpolator

App	Description
hello_interp	A bundle of small examples, showing how to access the core-local interpolator hardware, and use most of its features.

Multicore

App	Description
hello_multicore	Launch a function on the second core, printf some messages on each core, and pass data back and forth through the mailbox FIFOs.
multicore_fifo_irqs	On each core, register and interrupt handler for the mailbox FIFOs. Show how the interrupt fires when that core receives a message.
multicore_runner	Set up the second core to accept, and run, any function pointer pushed into its mailbox FIFO. Push in a few pieces of code and get answers back.

Pico Board

App	Description
blinky	Blink "hello, world" in Morse code on Pico's LED
button	Use Pico's BOOTSEL button as a regular button input, by temporarily suspending flash access.

Pico W Networking

These examples are for the Pico W, and are only available for PICO_BOARD=pico_w

App	Description
picow_access_point	Starts a WiFi access point, and fields DHCP requests.
picow_blink	Blinks the on-board LED (which is connected via the WiFi chip).
picow_iperf_server	Runs an "iperf" server for WiFi speed testing.
picow_ntp_client	Connects to an NTP server to fetch and display the current time.
picow_tcp_client	A simple TCP client. You can run python_test_tcp_server.py for it to connect to.
picow_tcp_server	A simple TCP server. You can use python_test_tcp_client.py to connect to it.
picow_tls_client	Demonstrates how to make a HTTPS request using TLS.
picow_wifi_scan	Scans for WiFi networks and prints the results.
picow_udp_beacon	A simple UDP transmitter.

FreeRTOS examples

These are examples of integrating Pico W networking under FreeRTOS, and require you to set the FREERTOS_KERNEL_PATH to point to the FreeRTOS Kernel.

App	Description
picow_freertos_iperf_server_nosys	Runs an "iperf" server for WiFi speed testing under FreeRTOS in NO_SYS=1 mode. The LED is blinked in another task
picow_freertos_iperf_server_sys	Runs an "iperf" server for WiFi speed testing under FreeRTOS in NO_SYS=0 (i.e. full FreeRTOS integration) mode. The LED is blinked in another task
picow_freertos_ping_nosys	Runs the lwip-contrib/apps/ping test app under FreeRTOS in NO_SYS=1 mode.
picow_freertos_ping_sys	Runs the lwip-contrib/apps/ping test app under FreeRTOS in NO_SYS=0 (i.e. full FreeRTOS integration) mode. The test app uses the lwIP socket API in this case.

Pico W Bluetooth

These examples are for the Pico W, and are only available for PICO_BOARD=pico_w. They are examples from the Blue Kitchen Bluetooth stack, see here for a full description.

By default, the Bluetooth examples are only built in one "mode" only (background, poll, or freertos), with the default being background. This can be changed by passing -DBTSTACK_EXAMPLE_TYPE=poll etc. to CMake, or all examples can be built (which may be slow) by passing -DBTSTACK_EXAMPLE_TYPE=all Freertos versions can only be built if FREERTOS_KERNEL_PATH is defined.

App	Description
picow_bt_example_a2dp_sink_demo	A2DP Sink - Receive Audio Stream and Control Playback.
picow_bt_example_a2dp_source_demo	A2DP Source - Stream Audio and Control Volume.
picow_bt_example_ancs_client_demo	LE ANCS Client - Apple Notification Service.
picow_bt_example_att_delayed_response	LE Peripheral - Delayed Response.
picow_bt_example_audio_duplex	Audio Driver - Forward Audio from Source to Sink.
picow_bt_example_avrcp_browsing_client	AVRCP Browsing - Browse Media Players and Media Information.
picow_bt_example_dut_mode_classic	Testing - Enable Device Under Test (DUT.c) Mode for Classic.
picow_bt_example_gap_dedicated_bonding	GAP bonding
picow_bt_example_gap_inquiry	GAP Classic Inquiry.
picow_bt_example_gap_le_advertisements	GAP LE Advertisements Scanner.
picow_bt_example_gap_link_keys	GAP Link Key Management (Classic.c).
picow_bt_example_gatt_battery_query	GATT Battery Service Client.
picow_bt_example_gatt_browser	GATT Client - Discover Primary Services.
picow_bt_example_gatt_counter	GATT Server - Heartbeat Counter over GATT.
picow_bt_example_gatt_device_information_query	GATT Device Information Service Client.
picow_bt_example_gatt_heart_rate_client	GATT Heart Rate Sensor Client.
picow_bt_example_gatt_streamer_server	Performance - Stream Data over GATT (Server.c).
picow_bt_example_hfp_ag_demo	HFP AG - Audio Gateway.
picow_bt_example_hfp_hf_demo	HFP HF - Hands-Free.
picow_bt_example_hid_host_demo	HID Host Classic.
picow_bt_example_hid_keyboard_demo	HID Keyboard Classic.
picow_bt_example_hid_mouse_demo	HID Mouse Classic.
picow_bt_example_hog_boot_host_demo	HID Boot Host LE.
picow_bt_example_hog_host_demo	HID Host LE.
picow_bt_example_hog_keyboard_demo	HID Keyboard LE.
picow_bt_example_hog_mouse_demo	HID Mouse LE.
picow_bt_example_hsp_ag_demo	HSP AG - Audio Gateway.
picow_bt_example_hsp_hs_demo	HSP HS - Headset.
picow_bt_example_le_credit_based_flow_control_mode_client	LE Credit-Based Flow-Control Mode Client - Send Data over L2CAP.
picow_bt_example_le_credit_based_flow_control_mode_server	LE Credit-Based Flow-Control Mode Server - Receive data over L2CAP.
picow_bt_example_led_counter	Hello World - Blinking a LED without Bluetooth.
picow_bt_example_le_mitm	LE Man-in-the-Middle Tool.
picow_bt_example_le_streamer_client	Performance - Stream Data over GATT (Client.c).
picow_bt_example_mod_player	Audio Driver - Play 80's MOD Song.
picow_bt_example_nordic_spp_le_counter	LE Nordic SPP-like Heartbeat Server.
picow_bt_example_nordic_spp_le_streamer	LE Nordic SPP-like Streamer Server.
picow_bt_example_sdp_general_query	SDP Client - Query Remote SDP Records.
picow_bt_example_sdp_rfcomm_query	SDP Client - Query RFCOMM SDP record.
picow_bt_example_sine_player	Audio Driver - Play Sine.
picow_bt_example_sm_pairing_central	LE Central - Test Pairing Methods.
picow_bt_example_sm_pairing_peripheral	LE Peripheral - Test Pairing Methods.
picow_bt_example_spp_and_gatt_counter	Dual Mode - SPP and LE Counter.
picow_bt_example_spp_and_gatt_streamer	Dual Mode - SPP and LE streamer.
picow_bt_example_spp_counter	SPP Server - Heartbeat Counter over RFCOMM.
picow_bt_example_spp_flowcontrol	SPP Server - RFCOMM Flow Control.
picow_bt_example_spp_streamer_client	Performance - Stream Data over SPP (Client.c).
picow_bt_example_spp_streamer	Performance - Stream Data over SPP (Server.c).
picow_bt_example_ublox_spp_le_counter	LE u-blox SPP-like Heartbeat Server.

Some Standalone Bluetooth examples (without all the common example build infrastructure) are also available:

App	Description
picow_ble_temp_sensor	Reads from the on board temperature sensor and sends notifications via BLE
picow_ble_temp_sensor_with_wifi	Same as above but also connects to Wi-Fi and starts an "iperf" server
picow_ble_temp_reader	Connects to on of the above "sensors" and reads the temperature

PIO

App	Description
hello_pio	Absolutely minimal example showing how to control an LED by pushing values into a PIO FIFO.
apa102	Rainbow pattern on on a string of APA102 addressable RGB LEDs.
differential_manchester	Send and receive differential Manchester-encoded serial (BMC).
hub75	Display an image on a 128x64 HUB75 RGB LED matrix.
i2c	Scan an I2C bus.
ir_nec	Sending and receiving IR (infra-red) codes using the PIO.
logic_analyser	Use PIO and DMA to capture a logic trace of some GPIOs, whilst a PWM unit is driving them.
manchester_encoding	Send and receive Manchester-encoded serial.
pio_blink	Set up some PIO state machines to blink LEDs at different frequencies, according to delay counts pushed into their FIFOs.
pwm	Pulse width modulation on PIO. Use it to gradually fade the brightness of an LED.
spi	Use PIO to erase, program and read an external SPI flash chip. A second example runs a loopback test with all four CPHA/CPOL combinations.
squarewave	Drive a fast square wave onto a GPIO. This example accesses low-level PIO registers directly, instead of using the SDK functions.
st7789_lcd	Set up PIO for 62.5 Mbps serial output, and use this to display a spinning image on a ST7789 serial LCD.
quadrature_encoder	A quadrature encoder using PIO to maintain counts independent of the CPU.
uart_rx	Implement the receive component of a UART serial port. Attach it to the spare Arm UART to see it receive characters.
uart_tx	Implement the transmit component of a UART serial port, and print hello world.
ws2812	Examples of driving WS2812 addressable RGB LEDs.
addition	Add two integers together using PIO. Only around 8 billion times slower than Cortex-M0+.

PWM

App	Description
hello_pwm	Minimal example of driving PWM output on GPIOs.
led_fade	Fade an LED between low and high brightness. An interrupt handler updates the PWM slice's output level each time the counter wraps.
measure_duty_cycle	Drives a PWM output at a range of duty cycles, and uses another PWM slice in input mode to measure the duty cycle.

Reset

App	Description
hello_reset	Perform a hard reset on some peripherals, then bring them back up.

RTC

App	Description
hello_rtc	Set a date/time on the RTC, then repeatedly print the current time, 10 times per second, to show it updating.
rtc_alarm	Set an alarm on the RTC to trigger an interrupt at a date/time 5 seconds into the future.
rtc_alarm_repeat	Trigger an RTC interrupt once per minute.

SPI

App	Description
bme280_spi	Attach a BME280 temperature/humidity/pressure sensor via SPI.
mpu9250_spi	Attach a MPU9250 accelerometer/gyoscope via SPI.
spi_dma	Use DMA to transfer data both to and from the SPI simultaneously. The SPI is configured for loopback.
spi_flash	Erase, program and read a serial flash device attached to one of the SPI controllers.
spi_master_slave	Demonstrate SPI communication as master and slave.
max7219_8x7seg_spi	Attaching a Max7219 driving an 8 digit 7 segment display via SPI
max7219_32x8_spi	Attaching a Max7219 driving an 32x8 LED display via SPI

System

App	Description
hello_double_tap	An LED blink with the pico_bootsel_via_double_reset library linked. This enters the USB bootloader when it detects the system being reset twice in quick succession, which is useful for boards with a reset button but no BOOTSEL button.
narrow_io_write	Demonstrate the effects of 8-bit and 16-bit writes on a 32-bit IO register.
unique_board_id	Read the 64 bit unique ID from external flash, which serves as a unique identifier for the board.

Timer

App	Description
hello_timer	Set callbacks on the system timer, which repeat at regular intervals. Cancel the timer when we're done.
periodic_sampler	Sample GPIOs in a timer callback, and push the samples into a concurrency-safe queue. Pop data from the queue in code running in the foreground.
timer_lowlevel	Example of direct access to the timer hardware. Not generally recommended, as the SDK may use the timer for IO timeouts.

UART

App	Description
hello_uart	Print some text from one of the UART serial ports, without going through stdio.
lcd_uart	Display text and symbols on a 16x02 RGB LCD display via UART
uart_advanced	Use some other UART features like RX interrupts, hardware control flow, and data formats other than 8n1.

USB Device

TinyUSB Examples

Most of the USB device examples come directly from the TinyUSB device examples directory here. Those that are supported on RP2040 devices are automatically included as part of the pico-examples build as targets named tinyusb_dev_<example_name>, e.g. https://github.com/hathach/tinyusb/tree/master/examples/device/hid_composite is built as tinyusb_dev_hid_composite.

At the time of writing, these examples are available:

• tinyusb_dev_audio_4_channel_mic
• tinyusb_dev_audio_test
• tinyusb_dev_board_test
• tinyusb_dev_cdc_dual_ports
• tinyusb_dev_cdc_msc
• tinyusb_dev_dfu
• tinyusb_dev_dfu_runtime
• tinyusb_dev_dynamic_configuration
• tinyusb_dev_hid_composite
• tinyusb_dev_hid_generic_inout
• tinyusb_dev_hid_multiple_interface
• tinyusb_dev_midi_test
• tinyusb_dev_msc_dual_lun
• tinyusb_dev_net_lwip_webserver
• tinyusb_dev_uac2_headset
• tinyusb_dev_usbtmc
• tinyusb_dev_video_capture
• tinyusb_dev_webusb_serial

Whilst these examples ably demonstrate how to use TinyUSB in device mode, their CMakeLists.txt is set up in a way tailored to how TinyUSB builds their examples within their source tree.

For a better example of how to configure CMakeLists.txt for using TinyUSB in device mode with the Raspberry Pi SDK see below:

SDK build example

App	Description
dev_hid_composite	A copy of the TinyUSB device example with the same name, but with a CMakeLists.txt which demonstrates how to add a dependency on the TinyUSB device libraries with the Raspberry Pi Pico SDK

Low Level example

App	Description
dev_lowlevel	A USB Bulk loopback implemented with direct access to the USB hardware (no TinyUSB)

USB Host

All the USB host examples come directly from the TinyUSB host examples directory here. Those that are supported on RP2040 devices are automatically included as part of the pico-examples build as targets named tinyusb_host_<example_name>, e.g. https://github.com/hathach/tinyusb/tree/master/examples/host/cdc_msc_hid is built as tinyusb_host_cdc_msc_hid.

At the time of writing, there is only one host example available:

• tinyusb_host_cdc_msc_hid

USB Dual Mode

USB Dual Mode uses PIO as a USB host controller and the RP2040 USB device controller as a device controller. All the USB dual examples come directly from the TinyUSB dual examples directory here. Those that are supported on RP2040 devices are automatically included as part of the pico-examples build as targets named tinyusb_dual_<example_name>, e.g. https://github.com/hathach/tinyusb/tree/master/examples/dual/host_hid_to_device_cdc is built as tinyusb_dual_host_hid_to_device_cdc.

At the time of writing, there is only one dual example available:

• tinyusb_dual_host_hid_to_device_cdc

Watchdog

App	Description
hello_watchdog	Set the watchdog timer, and let it expire. Detect the reboot, and halt.