Seeed Studio Xiao RP2040

The Seeed Studio Xiao RP2040 is a general purpose board supplied by Seeed Studio and it is compatible with the Raspberry Pi RP2040 ecosystem as they share the same RP2040 chip.

../../../../../_images/seeed-xiao-rp2040.jpg

Features

  • RP2040 microcontroller chip

  • Dual-core ARM Cortex M0+ processor, flexible clock running up to 133 MHz

  • 264KB of SRAM, and 2MB of onboard Flash memory

  • 11 digital pins, 4 analog pins, 11 PWM Pins

  • 1 I2C interface, 1 UART interface, 1 SPI interface, 1 SWD Bonding pad interface

  • USB Type-C interface

  • 1 user LED, 1 power LED, two LEDs for serial port downloading, 1 RGB LED

  • 1 RESET button, 1 BOOT button

Serial Console

By default a serial console appears on pins 6 (TX GPIO0) and pin 7 (RX GPIO1). This console runs a 115200-8N1. The board can be configured to use the USB connection as the serial console.

LEDs

There are 2 LEDs available for user:

  • A RGB LED connected to GPIO16 (PIN_LED_G), GPIO17 (PIN_LED_R), GPIO25 (PIN_LED_B).

  • A NeoPixel RGB LED connected to GPIO11 (NEOPIXEL_POWER) and GPIO12 (PIN_NEOPIXEL).

Buttons

There are 2 buttons available:

A RESET button and a BOOT button, which if held down when power is first applied to the board, will cause the RP2040 to boot into programming mode and appear as a storage device to a computer connected via USB. Saving a .UF2 file to this device will replace the Flash ROM contents on the RP2040.

Pin Mapping

Pads numbered anticlockwise from USB connector.

Pad

Signal

Notes

0

GPI26

D0/A0

1

GPI27

D1/A1

2

GPI28

D2/A2

3

GPI29

D3/A3

4

GPIO6

D4/SDA

5

GPIO7

D5/SCL

6

GPIO0

Default TX for UART0 serial console

7

GPIO1

Default RX for UART1 serial console/CSn

8

GPIO2

D8/SCK

9

GPIO3

D10/MOSI

10

GPIO4

D9/MicroSD

11

3V3

Power output to peripherals

12

Ground

13

VIN

+5V Supply to board

Power Supply

For general I/O pins:

Working voltage of MCU is 3.3V. Voltage input connected to general I/O pins may cause chip damage if it’ higher than 3.3V.

For power supply pins:

The built-in DC-DC converter circuit able to change 5V voltage into 3.3V allows to power the device with a 5V supply via VIN-PIN and via the USB connector.

Configurations

nsh

Basic NuttShell configuration (console enabled in UART0, at 115200 bps).

README.txt

README
======

This directory contains the port of NuttX to the Seeed Studio Xiao RP2040.
See https://wiki.seeedstudio.com/XIAO-RP2040/ for information about Seeed
Studio Xiao RP2040.

NuttX supports the following RP2040 capabilities:
  - UART  (console port)
    - GPIO 0 (UART0 TX) and GPIO 1 (UART0 RX) are used for the console.
  - I2C
  - SPI (master only)
  - DMAC
  - PWM
  - ADC
  - Watchdog
  - USB device
    - MSC, CDC/ACM serial and these composite device are supported.
    - CDC/ACM serial device can be used for the console.
  - PIO (RP2040 Programmable I/O)
  - Flash ROM Boot
  - SRAM Boot
    - If Pico SDK is available, nuttx.uf2 file which can be used in
      BOOTSEL mode will be created.
  - Persistent flash filesystem in unused flash ROM

NuttX also provides support for these external devices:

  - BMP180 sensor at I2C0 (don't forget to define I2C0 GPIOs at "I2C0 GPIO pin assign" in Board Selection menu)
  - INA219 sensor / module (don't forget to define I2C0 GPIOs at "I2C0 GPIO pin assign" in Board Selection menu)
  - WS2812 smart pixel support

There is currently no direct user mode access to these RP2040 hardware features:
  - SPI Slave Mode
  - SSI
  - RTC
  - Timers

Installation
============

1. Download Raspberry Pi Pico SDK and update submodule(cyw43-driver)

  $ git clone -b 1.4.0 https://github.com/raspberrypi/pico-sdk.git
  $ cd pico-sdk
  $ git submodule update --init --recursive lib/cyw43-driver

2. Set PICO_SDK_PATH environment variable

  $ export PICO_SDK_PATH=<absolute_path_to_pico-sdk_directory>

3. Configure and build NuttX

  $ git clone https://github.com/apache/nuttx.git nuttx
  $ git clone https://github.com/apache/nuttx-apps.git apps
  $ cd nuttx
  $ make distclean
  $ ./tools/configure.sh seeed-xiao-rp2040:nsh
  $ make V=1

4. Connect Seeed Studio Xiao RP2040 board to USB port while pressing BOOTSEL.
   The board will be detected as USB Mass Storage Device.
   Then copy "nuttx.uf2" into the device.
   (Same manner as the standard Pico SDK applications installation.)

5. To access the console, GPIO 0 and 1 pins must be connected to the
   device such as USB-serial converter.

   `usbnsh` configuration provides the console access by USB CDC/ACM serial
   devcice.  The console is available by using a terminal software on the USB
   host.

Defconfigs
==========

- nsh
    Minimum configuration with NuttShell

License exceptions
==================

The following files are originated from the files in Pico SDK.
So, the files are licensed under 3-Clause BSD same as Pico SDK.

- arch/arm/src/rp2040/rp2040_clock.c
- arch/arm/src/rp2040/rp2040_pll.c
- arch/arm/src/rp2040/rp2040_xosc.c
  - These are created by referring the Pico SDK clock initialization.

- arch/arm/src/rp2040/rp2040_pio.c
- arch/arm/src/rp2040/rp2040_pio.h
- arch/arm/src/rp2040/rp2040_pio_instructions.h
  - These provide the similar APIs to Pico SDK's hardware_pio APIs.

- arch/arm/src/rp2040/hardware/*.h
  - These are generated from rp2040.svd originally provided in Pico SDK.