Get Started With Pigweed And Bazel#

This guide provides a starting point for using Pigweed in a Bazel-based project. Bazel is the recommended build system for new projects using Pigweed.

Limitations#

  • Linux. Your development host must be running Linux. Bazel-based Pigweed projects are not yet supported on Windows. MacOS probably works but is unverified.

Setup#

  1. Install Bazel.

    Tip

    If you want to minimize system-wide installations, first install Node Version Manager and then install Bazelisk through NPM using npm install -g @bazel/bazelisk. If you use this workflow, remember that Bazel will only be available in the version of Node that’s currently activated through NVM.

  2. Clone the project:

    $ git clone --recursive https://pigweed.googlesource.com/example/echo

    Tip

    If you forgot the --recursive flag when cloning the code, run git submodule update --init.

All subsequent commands that you see in this guide should be run from the root directory of your new echo repo.

Build the project#

  1. Build the project for host and stm32f429i-disc1:

    $ bazel build //...

    You should see output like this:

    Starting local Bazel server and connecting to it...
INFO: Analyzed 7 targets (101 packages loaded, 17371 targets configured).
INFO: Found 7 targets...
INFO: From Linking src/echo:
/home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/bin/ld: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc_nano.a(libc_a-closer.o): in function `_close_r':
closer.c:(.text._close_r+0xc): warning: _close is not implemented and will always fail
/home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/bin/ld: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc_nano.a(libc_a-signalr.o): in function `_getpid_r':
signalr.c:(.text._getpid_r+0x0): warning: _getpid is not implemented and will always fail
/home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/bin/ld: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc_nano.a(libc_a-signalr.o): in function `_kill_r':
signalr.c:(.text._kill_r+0xe): warning: _kill is not implemented and will always fail
/home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/bin/ld: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc_nano.a(libc_a-lseekr.o): in function `_lseek_r':
lseekr.c:(.text._lseek_r+0x10): warning: _lseek is not implemented and will always fail
/home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/bin/ld: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc_nano.a(libc_a-readr.o): in function `_read_r':
readr.c:(.text._read_r+0x10): warning: _read is not implemented and will always fail
/home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/bin/ld: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/gcc_arm_none_eabi_toolchain/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/lib/thumb/v7e-m/nofp/libc_nano.a(libc_a-writer.o): in function `_write_r':
writer.c:(.text._write_r+0x10): warning: _write is not implemented and will always fail
INFO: Elapsed time: 6.716s, Critical Path: 1.98s
INFO: 40 processes: 3 internal, 37 linux-sandbox.
INFO: Build completed successfully, 40 total actions

Run the project locally#

  1. Run the project locally on your Linux development host:

    bazel run //src:echo

    You should see output like this:

    INFO: Analyzed target //src:echo (36 packages loaded, 202 targets configured).
INFO: Found 1 target...
Target //src:echo up-to-date:
  bazel-bin/src/echo
INFO: Elapsed time: 0.899s, Critical Path: 0.03s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action
INFO: Running command line: bazel-bin/src/echo

  2. Press Ctrl + C to stop running the project.

Flash the project onto a Discovery board#

If you have an STM32F429 Discovery board, you can run the project on that hardware.

Note

You don’t need this hardware to run the project. Because this project supports the host target, you can run everything on your Linux development host.

  1. Ensure your udev rules are set up to allow the user running the commands below to access the Discovery Board. For example, you may want to add the following rule as /etc/udev/rules.d/99-stm32f329i-disc1.rules:

    ATTRS{idVendor}=="0483", ATTRS{idProduct}=="374b", MODE="664", GROUP="plugdev"

    The user running the commands needs to be in the group plugdev.

  2. Connect the Discovery board to your development host with a USB cable. Use the Mini-B USB port on the Discovery board, not the Micro-B port.

  3. Flash the project to the Discovery board:

    $ bazel run //tools:flash

    You should see output like this:

    INFO: Analyzed target //tools:flash (52 packages loaded, 2760 targets configured).
INFO: Found 1 target...
Target //tools:flash up-to-date:
  bazel-bin/tools/flash
INFO: Elapsed time: 0.559s, Critical Path: 0.04s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action
INFO: Running command line: bazel-bin/tools/flash
binary Rlocation is: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/execroot/__main__/bazel-out/k8-fastbuild/bin/src/echo.elf
openocd Rlocation is: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/openocd/bin/openocd
openocd config Rlocation is: /home/xyz/.cache/bazel/_bazel_xyz/8c700b5cf88b83b789ceaf0e4e271fac/external/pigweed/targets/stm32f429i_disc1/py/stm32f429i_disc1_utils/openocd_stm32f4xx.cfg
xPack OpenOCD x86_64 Open On-Chip Debugger 0.11.0+dev (2021-12-07-17:30)
Licensed under GNU GPL v2
For bug reports, read
  http://openocd.org/doc/doxygen/bugs.html
DEPRECATED! use 'adapter driver' not 'interface'
DEPRECATED! use 'adapter serial' not 'hla_serial'
Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
srst_only separate srst_nogate srst_open_drain connect_deassert_srst

Info : clock speed 2000 kHz
Info : STLINK V2J25M14 (API v2) VID:PID 0483:374B
Info : Target voltage: 2.837377
Info : stm32f4x.cpu: Cortex-M4 r0p1 processor detected
Info : stm32f4x.cpu: target has 6 breakpoints, 4 watchpoints
Info : gdb port disabled
Info : Unable to match requested speed 2000 kHz, using 1800 kHz
Info : Unable to match requested speed 2000 kHz, using 1800 kHz
target halted due to debug-request, current mode: Thread
xPSR: 0x01000000 pc: 0x08000708 msp: 0x20030000
Info : Unable to match requested speed 8000 kHz, using 4000 kHz
Info : Unable to match requested speed 8000 kHz, using 4000 kHz
** Programming Started **
Info : device id = 0x20016419
Info : flash size = 2048 kbytes
Info : Dual Bank 2048 kiB STM32F42x/43x/469/479 found
Info : Padding image section 0 at 0x08000010 with 496 bytes
** Programming Finished **
** Resetting Target **
Info : Unable to match requested speed 2000 kHz, using 1800 kHz
Info : Unable to match requested speed 2000 kHz, using 1800 kHz
shutdown command invoked

Communicate with the project over serial#

After you’ve flashed the project onto your Discovery board, your Linux development host can communicate with the project over a serial terminal like miniterm.

  1. Transmit and receive characters:

    $ bazel run //tools:miniterm -- /dev/ttyACM0 --filter=debug

    After typing hello and pressing Ctrl + ] to exit you should see output like this:

    INFO: Analyzed target //tools:miniterm (41 packages loaded, 2612 targets configured).
INFO: Found 1 target...
Target //tools:miniterm up-to-date:
  bazel-bin/tools/miniterm
INFO: Elapsed time: 0.373s, Critical Path: 0.02s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action
INFO: Running command line: bazel-bin/tools/miniterm /dev/ttyACM0 '--filter=debug'
--- Miniterm on /dev/ttyACM0  115200,8,N,1 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
 [TX:'h']  [RX:'h'] h [TX:'e']  [RX:'e'] e [TX:'l']  [RX:'l'] l [TX:'l']  [RX:'l'] l [TX:'o']  [RX:'o'] o
--- exit ---

Questions? Comments? Feedback?#

Please join our Discord and talk to us in the #bazel-build channel or file a bug.