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RPi-Pico

README.md

Getting Started

Details of the Pi Pico support in wolfSSL can be found in the wolfcrypt/src/port/pi_pico/README.md.

This demonstration compiles several different utilities, including the wolfCrypt benchmark and test suite.

Prerequisites

You of course need a Pi Pico based board. Any RP2040 / RP2350 based board should work, as long as it has a USB port to upload firmware to.

You need to have the Raspberry Pi Pico SDK GitHub repository somewhere on your system. You also need the ARM compiler and CMake installed, in Debian / Ubuntu you can do this using:

sudo apt install cmake gcc-arm-none-eabi libnewlib-arm-none-eabi libstdc++-arm-none-eabi-newlib

If you wish to use RISC-V with the RP2350 (ARM mode is default), you will need a riscv32-unknown-elf-gcc compiler. You can search for binaries for this, or compile the RISC-V GNU Toolchain in multilib mode. You will also need to add symlinks from riscv64-unknown-* to riscv32-unknown-elf-* if you build the toolchain from source. This is because the multilib mode compiler is both 32bit and 64bit.

1. Set an export to the wolfSSL source directory.

export WOLFSSL_ROOT=/path/to/wolfssl/source

2. Setup pico-sdk and set PICO_SDK_PATH

export PICO_SDK_PATH=/path/to/pico-sdk

3. Set FREERTOS_KERNEL_PATH

If you want to use TCP/TLS server or client, You also need to have the FreeRTOS-Kernel GitHub repository.

export FREERTOS_KERNEL_PATH=/path/to/FreeRTOS-Kernel

4. cmake and make

The following CMAKE options are available:

  • PICO_BOARD - This should be set to pico for a Pi Pico, pico_w for a Pi Pico with WiFi or pico2 for a Pi Pico 2. A full list of boards for this option can be found here, just ignore the .h at the end.
  • USE_WIFI - Build the tests that use WiFi, only works when PICO_BOARD defined has a CYW43 WiFi chip.
  • USE_UART - Output to UART instead of USB, for the Pi Debug Probe.
  • WIFI_SSID - The SSID to connect to (if USE_WIFI is set).
  • WIFI_PASSWORD - The password used for the WiFi network (if USE_WIFI is set).
  • TEST_TCP_SERVER_IP - The test server to connect to for the TCP client test (if USE_WIFI is set).

To use the RP2350 in RISC-V mode, add -DPICO_PLATFORM=rp2350-riscv.

$ cd RPi-Pico
$ cmake -DPICO_BOARD=pico_w ..
$ make

The build produces the following UF2 images:

  • testwolfcrypt.uf2

  • benchmark.uf2

  • Wifi.uf2

  • tcp_Client.uf2

  • tls_Client.uf2

  • tcp_Server.uf2

  • tls_Server.uf2

5. Upload to the Pico

Hold the boot button and plug the Pico into your computer, you can then drag/drop a .uf2 to the Pico. It will stop becoming a USB mass storage device and run immediately once the upload is complete. Alternatively, you can use picotool to upload a file:

sudo picotool load benchmark.uf2
sudo picotool reboot

6. Serial output

If you have not set USE_UART, once rebooted the USB port will turn into an "Abstract Control Module" serial port. On Linux this will likely be /dev/ttyACM0, or a number higher than 0 if you already have one. On macOS this will be something like /dev/cu.usbmodemXXXX. The baud rate of this port is 115200.

In Linux, most repositories have minicom. Install this using your package manager and run:

minicom -b 115200 -o -D /dev/ttyACM0

If you need to exit at any time, it is CTRL-A followed by CTRL-X.