Waveshare RP2040 Zero

The Waveshare RP2040 Zero is a general purpose board supplied by Waveshare.

../../../../../_images/WaveshareRP2040Zero.png

Features

  • RP2040 microcontroller chip

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

  • 264kB of SRAM, and 2MB of on-board Flash memory

  • Castellated module allows soldering direct to carrier boards

  • USB 1.1 Host and Device support

  • Low-power sleep and dormant modes

  • Drag & drop programming using mass storage over USB

  • 20 multi-function GPIO pins

  • 2× SPI, 2× I2C, 2× UART, 3× 12-bit ADC, 16× controllable PWM channels

  • Accurate clock and timer on-chip

  • Temperature sensor

  • Accelerated floating point libraries on-chip

  • 8 × Programmable IO (PIO) state machines for custom peripheral support

Serial Console

By default a serial console appears on pins 23 (TX GPIO0) and pin 22 (RX GPIO1). This console runs a 115200-8N1.

The board can be configured to use the USB connection as the serial console.

Buttons and LEDs

A ws2812 (NeoPixel) smart RGB LED controlled by GPIO16 (data).

There is a BOOT button which if held down when power is first applied or the RESET button is pressed will cause the RP2040 to boot into program mode and appear as a storage device to a USB connecter. 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

1

5V

2

Ground

3

3.3V

4

GPIO29

5

GPIO28

6

GPIO27

7

GPIO26

8

GPIO15

9

GPIO14

10

GPIO13

11

GPIO12

12

GPIO11

Default TX for SPI1

13

GPIO10

Default SCK for SPI1

14

GPIO9

Default CSn for SPI1

15

GPIO8

Default RX for SPI1

16

GPIO7

Default SCL for I2C1

17

GPIO6

Default SDA for I2C1

18

GPIO5

Default SCL for I2C0

19

GPIO4

Default SDA for I2C0

20

GPIO3

21

GPIO2

22

GPIO1

Default RX for UART0 serial console

23

GPIO0

Default TX for UART0 serial console

Power Supply

The Waveshare RP2040 Zero can be powered via the USB connector, or by supplying +5V to pin 1.

The RP2040 runs on 3.3 volts. This is supplied by an onboard voltage regulator.

Supported Capabilities

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

  • WiFi wireless communication

There is currently no direct user mode access to these RP2040 hardware features:

  • SPI Slave Mode

  • SSI

  • RTC

  • Timers

NuttX also provide 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)

  • SHT4X sensor at I2C0

  • Pico Display Pack (ST7789 LCD)

    • RGB leds and buttons are not supported yet.

  • Pico Audio Pack (PCM5100A I2S DAC)

    • I2S interface is realized by PIO.

  • WS2812 smart pixel support

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 waveshare-rp2040-zero:nsh
$ make V=1

  1. Connect Raspberry Pi Pico 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.)

  2. 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 device. The console is available by using a terminal software on the USB host.

Configurations

gpio

NuttShell configuration (console enabled in UART0, at 115200 bps) with GPIO examples.

nsh

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

usbnsh

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

ws2812

Basic NuttShell configuration with WS2812 driver and example enabled. Console is enabled over USB 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.