Pimoroni Pico Plus 2

Tags: chip:rp2350

The Pimoroni Pico Plus 2 is an RP2350B based board in the Raspberry Pi Pico form factor, with a USB-C connector, a large 16 MiB of flash and 8 MiB of external QSPI PSRAM.

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Features

  • RP2350B microcontroller chip (QFN-80 variant)

  • Dual-core Arm Cortex-M33 processor running up to 150 MHz

  • 520 KiB of internal SRAM

  • 16 MiB of on-board QSPI flash memory

  • 8 MiB of on-board QSPI PSRAM (APS6404) on chip select 1

  • USB-C connector, USB 1.1 host and device support

  • Qwiic / STEMMA QT (I2C) connector

  • SP/CE debug and expansion connectors

  • Reset and BOOTSEL buttons

  • 48 multi-function GPIO pins broken out on castellated and through-hole pads

  • Drag & drop programming using mass storage over USB

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

Serial Console

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

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

Buttons and LEDs

The user LED is controlled by GPIO25 and is configured as autoled by default.

A BOOTSEL button, which if held down when power is first applied to the board, will cause the RP2350 to boot into programming mode and appear as a storage device to the computer connected via USB. Saving a .uf2 file to this device will replace the flash contents. A separate RESET button is also provided.

PSRAM

The distinguishing feature of the Pimoroni Pico Plus 2 is the 8 MiB of external QSPI PSRAM (an APS6404 part) hanging off the QMI on chip select 1 (GPIO47). NuttX detects the PSRAM at boot, switches it to quad mode and maps it read/write at 0x11000000.

PSRAM support is enabled by default in the nsh configuration (CONFIG_RP23XX_PSRAM), which adds the 8 MiB to the main heap. The chip select pin is configured with CONFIG_RP23XX_PSRAM_CS1_GPIO (47 on this board) and the way the PSRAM is exposed to the memory manager (single heap, separate heap, or user heap) is selectable. See the RP23xx PSRAM section for the details of each mode.

Note

The PSRAM is considerably slower than the internal SRAM. The QMI is shared with the flash: writing to the flash goes through the bootrom, which reconfigures the QMI for chip select 0 and disturbs the PSRAM configuration on chip select 1. rp23xx_psram_restore() re-applies it and is intended to be called from the flash write path after each erase or program.

Supported Capabilities

NuttX supports the following Pico Plus 2 capabilities:

  • UART (console port)

    • GPIO 0 (UART0 TX) and GPIO 1 (UART0 RX) are used for the console.

  • External QSPI PSRAM (8 MiB)

  • I2C

  • SPI (master only)

  • DMAC

  • PWM

  • ADC

  • Watchdog

  • USB device

    • MSC, CDC/ACM serial and composite devices are supported.

    • CDC/ACM serial device can be used for the console.

  • PIO (RP2350 Programmable I/O)

  • Flash ROM Boot

  • SRAM Boot

    • If the Pico SDK is available, a nuttx.uf2 file which can be used in BOOTSEL mode will be created.

  • Persistent flash filesystem in unused flash ROM

Installation

  1. Download and install the toolchain and, optionally, the Raspberry Pi Pico SDK (needed to generate the nuttx.uf2 image).

$ git clone -b 2.2.0 --recurse-submodules https://github.com/raspberrypi/pico-sdk.git
$ 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 pimoroni-pico-2-plus:nsh
$ make V=1

  1. Connect the board to the USB port while pressing BOOTSEL. The board will be detected as a USB Mass Storage Device. Then copy nuttx.uf2 into the device (the same way as standard Pico SDK applications).

  2. To access the console, connect GPIO 0 and 1 to a device such as a USB-serial converter, or use the usbnsh configuration for a console over USB CDC/ACM.

Configurations

nsh

Basic NuttShell configuration (console enabled on UART0, at 115200 bps) with the external PSRAM added to the main heap.

usbnsh

Basic NuttShell configuration (console enabled via USB CDC/ACM).

smp

Basic NuttShell configuration (console enabled on UART0, at 115200 bps) with both Arm cores enabled.

audiopack

Configuration for the Pimoroni Pico Audio Pack.

composite

USB composite device configuration.

usbmsc

USB mass storage device configuration.

userled

Configuration demonstrating user-controlled LED access.