Raspberry Pi Pico#
Warning
This target is in an early state and is under active development. Usability is not very polished, and many features/configuration options that work in upstream Pi Pico CMake build have not yet been ported to the GN build.
Setup#
To use this target, Pigweed must be set up to build against the Raspberry Pi
Pico SDK. This can be downloaded via pw package
, and then the build must be
manually configured to point to the location of the downloaded SDK.
pw package install pico_sdk
gn args out
# Add this line.
PICO_SRC_DIR = getenv("PW_PACKAGE_ROOT") + "/pico_sdk"
Linux#
On linux, you may need to update your udev rules at
/etc/udev/rules.d/49-pico.rules
to include the following:
SUBSYSTEMS=="usb", ATTRS{idVendor}=="2e8a", ATTRS{idProduct}=="0004", MODE:="0666"
KERNEL=="ttyACM*", ATTRS{idVendor}=="2e8a", ATTRS{idProduct}=="0004", MODE:="0666"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="2e8a", ATTRS{idProduct}=="0003", MODE:="0666"
KERNEL=="ttyACM*", ATTRS{idVendor}=="2e8a", ATTRS{idProduct}=="0003", MODE:="0666"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="2e8a", ATTRS{idProduct}=="000a", MODE:="0666"
KERNEL=="ttyACM*", ATTRS{idVendor}=="2e8a", ATTRS{idProduct}=="000a", MODE:="0666"
Usage#
The Pi Pico is configured to output logs and test results over USB serial at a baud rate of 115200.
Once the pico SDK is configured, the Pi Pico will build as part of the default GN build:
ninja -C out
Pigweed’s build will produce ELF and UF2 files for each unit test built for the Pi Pico.
Flashing#
Flashing the Pi Pico is two easy steps:
While holding the button on the Pi Pico, connect the Pico to your computer via the micro USB port.
Copy the desired UF2 firmware image to the RPI-RP2 volume that enumerated when you connected the Pico.
Testing#
Unlike some other targets, the RP2040 does not automatically run tests on boot. To run a test, flash it to the RP2040 and connect to the serial port and then press the spacebar to start the test:
$ python -m serial.tools.miniterm --raw /dev/ttyACM0 115200
--- Miniterm on /dev/cu.usbmodem142401 115200,8,N,1 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---INF [==========] Running all tests.
INF [ RUN ] Status.Default
INF [ OK ] Status.Default
INF [ RUN ] Status.ConstructWithStatusCode
INF [ OK ] Status.ConstructWithStatusCode
INF [ RUN ] Status.AssignFromStatusCode
INF [ OK ] Status.AssignFromStatusCode
INF [ RUN ] Status.Ok_OkIsTrue
INF [ OK ] Status.Ok_OkIsTrue
INF [ RUN ] Status.NotOk_OkIsFalse
INF [ OK ] Status.NotOk_OkIsFalse
INF [ RUN ] Status.Code
INF [ OK ] Status.Code
INF [ RUN ] Status.EqualCodes
INF [ OK ] Status.EqualCodes
INF [ RUN ] Status.IsError
INF [ OK ] Status.IsError
INF [ RUN ] Status.IsNotError
INF [ OK ] Status.IsNotError
INF [ RUN ] Status.Strings
INF [ OK ] Status.Strings
INF [ RUN ] Status.UnknownString
INF [ OK ] Status.UnknownString
INF [ RUN ] Status.Update
INF [ OK ] Status.Update
INF [ RUN ] StatusCLinkage.CallCFunctionWithStatus
INF [ OK ] StatusCLinkage.CallCFunctionWithStatus
INF [ RUN ] StatusCLinkage.TestStatusFromC
INF [ OK ] StatusCLinkage.TestStatusFromC
INF [ RUN ] StatusCLinkage.TestStatusStringsFromC
INF [ OK ] StatusCLinkage.TestStatusStringsFromC
INF [==========] Done running all tests.
INF [ PASSED ] 15 test(s).
This is done because the serial port enumerated by the Pi Pico goes away on reboot, so it’s not safe to run tests until the port has fully enumerated and a terminal has connected. To avoid races, the Pico will just wait until it receives the space character (0x20) as a signal to start running the tests.
The RP2040 does not yet provide an automated test runner with build system integration.