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boards/rpi-picow: add board documentation
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/** | ||
@defgroup boards_rpi_pico_w Raspberry Pi Pico W | ||
@ingroup boards | ||
@brief Support for the RP2040 based Raspberry Pi Pico W board | ||
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## Overview | ||
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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. | ||
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## Hardware | ||
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Raspberry Pi Pico W (third from left) and Pico WH (forth from right). | ||
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![Raspberry Pi Pico family](https://www.raspberrypi.com/documentation/microcontrollers/images/four_picos.jpg) | ||
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### MCU | ||
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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. | ||
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| 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](https://datasheets.raspberrypi.com/picow/pico-w-datasheet.pdf) | | ||
| Wireless chip | [Infineon CYW43439 Datasheet](https://www.infineon.com/dgdl/Infineon-CYW43439-DataSheet-v03_00-EN.pdf?fileId=8ac78c8c8386267f0183c320336c029f) | | ||
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(*) Currently not implemented in the RIOT OS. | ||
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### User Interface | ||
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1 button (also used for boot selection) and 1 LED: | ||
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| Device | PIN | | ||
|:------ |:---------------- | | ||
| LED0 | WL_GPIO0 (*) | | ||
| SW0 | QSPI_SS_N (**) | | ||
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(*) In the Pico W LED0 is directly connected to the Infineon CYW43439 module, | ||
and cannot be directly controlled by MCU. | ||
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(**) 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. | ||
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### Pinout | ||
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![Pinout Diagram of RPi Pico W](https://www.raspberrypi.com/documentation/microcontrollers/images/picow-pinout.svg) | ||
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## Flashing the Board | ||
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### Flashing the Board Using the Bootloader | ||
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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: | ||
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``` | ||
make BOARD=rpi-picow flash | ||
``` | ||
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This is default flashing option using elf2uf2 PROGRAMMER. If the storage is | ||
not automatically mounted to `/media/<USER_NAME>/RPI-RP2`, you can overwrite | ||
the path by exporting the shell environment variable `ELF2UF2_MOUNT_PATH`. | ||
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### Flashing the Board Using OpenOCD | ||
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Currently (June 2021), only two methods for debugging via OpenOCD are supported: | ||
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1. Using a bit-banging low-level adapter, e.g. via the GPIOs of a Raspberry Pi 4B | ||
2. Using a virtual CMSIS-DAP adapter provided by the second CPU core via | ||
https://github.com/majbthrd/pico-debug | ||
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Option 2 requires no additional hardware however, you need to | ||
first "flash" the gimme-cache variant of [pico-debug](https://github.com/majbthrd/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](https://github.com/majbthrd/pico-debug/releases) 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: | ||
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``` | ||
make BOARD=rpi-pico PROGRAMMER=openocd flash | ||
``` | ||
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@warning The `rpi-pico` virtual debugger is not persistent and needs to be "flashed" into RAM | ||
again after each cold boot. | ||
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@note As of July 2021, the latest stable release of OpenOCD does not yet support the RP2040 | ||
MCU. Instead, compile the current `master` branch from the upstream OpenOCD source. | ||
The OpenOCD fork of the Raspberry Pi foundation is incompatible with OpenOCD | ||
configuration provided, so please stick with upstream OpenOCD. | ||
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### Flashing the Board Using J-Link | ||
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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: | ||
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``` | ||
make BOARD=rpi-pico PROGRAMMER=jlink flash | ||
``` | ||
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## Accessing RIOT shell | ||
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This board's default access to RIOT shell is via UART (UART0 TX - pin 1, UART0 RX - pin 2). | ||
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The default baud rate is 115 200. | ||
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The simplest way to connect to the shell is the execution of the command: | ||
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``` | ||
make BOARD=rpi-pico term | ||
``` | ||
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@warning Raspberry Pi Pico board is not 5V tolerant. Use voltage divider or logic level shifter when connecting to 5V UART. | ||
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## On-Chip Debugging | ||
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There are currently (June 2021) few hardware options for debugging the Raspberry Pi Pico: | ||
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1. Via J-Link using one of Seggers debuggers | ||
2. 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) | ||
3. Via a recently updated [Black Magic Probe](https://github.com/blacksphere/blackmagic) | ||
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In addition, a software-only option is possible using | ||
[pico-debug](https://github.com/majbthrd/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: | ||
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``` | ||
make BOARD=rpi-picow debug | ||
``` | ||
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***Beware:*** The `rpi-pico` 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. | ||
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## Known Issues / Problems | ||
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### Early state Implementation | ||
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Currently no support for the following peripherals is implemented: | ||
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- Timers | ||
- ADC | ||
- SPI | ||
- I2C | ||
- USB | ||
- PIO | ||
- RTC | ||
- Watchdog | ||
- SMP support (multi CPU support is not implemented in RIOT) | ||
- Infineon CYW 43439 wireless chip | ||
*/ |