7.2 KiB
@defgroup boards_rpi_pico_w Raspberry Pi Pico W @ingroup boards @brief Support for the RP2040 based Raspberry Pi Pico W board
Overview
The Raspberry Pi Pico W and Pico WH (with headers) is a board with RP2040 MCU, a custom dual core ARM Cortex-M0+ MCU with relatively high CPU clock, plenty of RAM, some unique peripheral (the Programmable IO) and the Infineon CYW43439 wireless chip.
Hardware
@image html https://www.raspberrypi.com/documentation/computers/images/pico-w.png "Raspberry Pi Pico W" width=50%
Raspberry Pi Pico W is provided in two versions - without and with headers, the second one is called Pico WH. Detailed photos can be found at Raspberry Pi Pico family.
MCU
The Programmable IO (PIO) peripheral and the SSI/QSPI peripheral that supports execution from flash (XIP) are the most distinguishing features of the MCU. The latter is especially important, since the RP2040 contains no internal flash.
| MCU | RP2040 |
|---|---|
| Family | (2x) ARM Cortex-M0+ |
| Vendor | Raspberry Pi |
| RAM | 264 KiB |
| Flash | 2 MiB (up to 16 MiB) |
| Frequency | up to 133 MHz |
| FPU | no |
| PIOs | 8 |
| Timers | 1 x 64-bit |
| ADCs | 1x 12-bit (4 channels + temperature sensor) |
| UARTs | 2 |
| SPIs | 2 |
| I2Cs | 2 |
| RTCs | 1 |
| USBs | 1 (USB 2.0) |
| Watchdog | 1 |
| SSI/QSPI | 1 (connected to flash, with XIP support) |
| WiFi | via wireless chip (Infineon CYW43439) (*) |
| Bluetooth | via wireless chip (Infineon CYW43439) (*) |
| Vcc | 1.62V - 3.63V |
| Datasheet | Datasheet |
| Wireless chip | Infineon CYW43439 Datasheet |
(*) Currently not implemented in the RIOT OS.
User Interface
1 button (also used for boot selection) and 1 LED:
| Device | PIN |
|---|---|
| LED0 | WL_GPIO0 (*) |
| SW0 | QSPI_SS_N (**) |
(*) In the Pico W LED0 is directly connected to the Infineon CYW43439 module, and cannot be directly controlled by MCU.
(**) Since the switch is connected to the chip-select pin of the QSPI interface the flash chip RIOT is running from via XIP, the switch is difficult to read out from software. This is currently not supported.
Pinout
Flashing the Board
Flashing the Board Using the Bootloader
Connect the device to your Micro-USB cable while the button (labeled BOOTSEL
on the silkscreen of the PCB) is pressed to enter the bootloader. The pico
will present itself as a storage medium to the system, to which a UF2 file
can be copied perform the flashing of the device. This can be automated by
running:
make BOARD=rpi-pico-w flash
This is default flashing option using picotool PROGRAMMER.
Flashing the Board Using OpenOCD
Currently (June 2021), only two methods for debugging via OpenOCD are supported:
- Using a bit-banging low-level adapter, e.g. via the GPIOs of a Raspberry Pi 4B
- Using a virtual CMSIS-DAP adapter provided by the second CPU core via https://github.com/majbthrd/pico-debug
Option 2 requires no additional hardware however, you need to
first "flash" the gimme-cache variant of pico-debug
into RAM using the UF2 bootloader. For this, plug in the USB cable while holding down the BOOTSEL
button of the Pico and copy the pico-debug-gimmecache.uf2 from the
latest pico-debug release into the virtual FAT
formatted drive the bootloader provides. Once this drive is unmounted again, this will result in
the Raspberry Pi Pico showing up as CMSIS-DAP debugger. Afterwards run:
make BOARD=rpi-pico-w PROGRAMMER=openocd flash
@warning The rpi-pico-w virtual debugger is not persistent and needs to be "flashed" into RAM
again after each cold boot.
@note The RP2040 MCU is supported from OpenOCD version 0.12.0 onwards.
Flashing the Board Using J-Link
Connect the Board to an Segger J-Link debugger, e.g. the EDU mini debugger is relatively affordable, but limited to educational purposes. Afterwards run:
make BOARD=rpi-pico-w PROGRAMMER=jlink flash
Accessing RIOT shell
This board's default access to RIOT shell is via UART (UART0 TX - pin 1, UART0 RX - pin 2).
The default baud rate is 115 200.
The simplest way to connect to the shell is the execution of the command:
make BOARD=rpi-pico-w term
@warning Raspberry Pi Pico board is not 5V tolerant. Use voltage divider or logic level shifter when connecting to 5V UART.
On-Chip Debugging
There are currently (June 2021) few hardware options for debugging the Raspberry Pi Pico:
- Via J-Link using one of Seggers debuggers
- Via OpenOCD using a low-level bit-banging debugger (e.g. a Raspberry Pi 4B with the GPIOs connected to the Raspberry Pi Pico via jump wires)
- Via a recently updated Black Magic Probe
In addition, a software-only option is possible using pico-debug. The default linker script reserved 16 KiB of RAM for this debugger, hence just "flash" the "gimme-cache" flavor into RAM using the UF2 bootloader. Once this is done, debugging is as simple as running:
make BOARD=rpi-pico-w debug
Beware: The rpi-pico-w virtual debugger is not persistent and needs to be "flashed"
into RAM again after each cold boot. The initialization code of RIOT now seems to play well with the
debugger, so it remains persistent on soft reboots. If you face issues with losing connection to
the debugger on reboot, try monitor reset init in GDB to soft-reboot instead.
Known Issues / Problems
Early State Implementation
Currently no support for the following peripherals is implemented:
- USB
- RTC
- Watchdog
- SMP support (multi CPU support is not implemented in RIOT)
- Infineon CYW 43439 wireless chip
The I2C peripheral is implemented through the PIO.