Nuttx Guide

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Мови (Ukrainian)

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Seeed Studio XIAO RP2040 ​

chip: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.

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 12 3V3 Ground Power output to peripherals 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.

Installation ​

  1. Download Raspberry Pi Pico SDK.
 git clone -b 2.0.0 https://github.com/raspberrypi/pico-sdk.git
  1. Download and install picotool

Instructions can be found here: https://github.com/raspberrypi/picotool

If you are on Arch Linux, you can install the picotool through the AUR:

 yay -S picotool
  1. Set PICO_SDK_PATH environment variable
 export PICO_SDK_PATH=<absolute_path_to_pico-sdk_directory>
  1. 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

  1. Connect the Seeed Studio Xiao RP2040 board to USB port while pressing BOOTSEL (small button marked "B"). 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)

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

    [usbnsh]{.title-ref} configuration provides the console access by USB CDC/ACM serial device. The console is available by using a terminal software on the USB host.

Configurations ​

nsh ​

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

userled ​

This is an nsh configuration with added support for user LEDs.

usbnsh ​

Basic NuttShell configuration using CDC/ACM serial (console enabled in USB Port, at 115200 bps).

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.