Sense

git clone https://pigweed.googlesource.com/pigweed/showcase/sense

Welcome to Pigweed Sense, a tour of key Pigweed components experienced through an imagined air quality product.

Please visit Sense: An interactive tour through Pigweed to get started.

Trying out changes to Pigweed with Pigweed Sense

If you'd like to test out changes to the main Pigweed code with Pigweed Sense, you will need to alter the your Pigweed Sense MODULE.bazel file to point to a local Pigweed checkout.

The typical workflow is to have the Pigweed and Pigweed Sense checkouts be subdirectories of the same parent directory.

/path/to/your/checkouts/
├── sense/
└── pigweed/

If you haven't yet cloned the Pigweed repository, you can do so with:

git clone https://pigweed.googlesource.com/pigweed/pigweed

Once that is done, you can modify the Sense MODULE.bazel to switch to using the local checkout.

First locate the existing “pigweed” module definition. It will look something like this:

git_override(
    module_name = "pigweed",
    # ROLL: Warning: this entry is automatically updated.
    # ROLL: Last updated 2025-10-05.
    # ROLL: By https://cr-buildbucket.appspot.com/build/8701840885187145297.
    commit = "85ff7d8715ad7bcff4a1286f2d2d2139cbe11291",
    remote = "https://pigweed.googlesource.com/pigweed/pigweed",
)

Change it instead:

# Override for local Pigweed development.
local_path_override(
    module_name = "pigweed",
    path = "../pigweed",
)

Once you've landed changes to Pigweed, and our rollers have updated the Pigweed Sense dependencies, you can revert the MODULE.bazel changes.

Debugging Pigweed Sense issues

GDB with OpenOCD as a bridge

On Linux, MacOS, and Windows (with MSYS2) You can use OpenOCD to create a bridge for gdb.

However if you have a Pico2 (rp2350), you must build OpenOCD from source, as the latest official release build (0.12.0) does not include support.

The Raspberry Pi Foundation also maintains it's own pi-focused fork of the OpenCD sources at https://github.com/raspberrypi/openocd which supports the rp2350. You can download prebuilt binaries for it from https://github.com/raspberrypi/pico-sdk-tools.

If you are building OpenOCD from it source code, you can find some notes on this thread since the cmsis-dap.cfg driver support for the Raspberry Pi Debug Probe isn't necessarily included by default.

https://forums.raspberrypi.com/viewtopic.php?p=2322149#p2322149

Once you have a working OpenOCD installation supporting your target, you can launch it in a shell session to start it as a bridge server for gdb.

# Note: Use target/rp2040.cfg instead for the original Pico.
openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "adapter speed 5000"

You can then launch gdb to connect to the bridge, and to reset the device to start with gdb at the initial entry point, and to trap on any ARM Cortex-M hardware events (such as a bus error or divide by zero).

arm-none-eabi-gdb -ex "target extended-remote :3333" \
        -ex "monitor reset init" \
        -ex "monitor cortex_m vector_catch all" \
        path/to/target.elf

For example:

# Note: Switch "rp23500" to "rp2040" below if you have the original Pico.
# Note: You will need to stop and later restart OpenOCD to flash the target.
# After: bazel run //apps/blinky:flash_rp2350
$ arm-none-eabi-gdb -ex "target extended-remote :3333" \
        -ex "monitor reset halt" \
        -ex "monitor cortex_m vector_catch all" \
        bazel-bin/apps/blinky/rp2350_blinky.elf
# [... gdb startup messages ... ]
Reading symbols from bazel-bin/apps/blinky/rp2350_blinky.elf...
Remote debugging using :3333
warning: multi-threaded target stopped without sending a thread-id, using first non-exited thread
0x00000088 in ?? ()
[rp2350.cm0] halted due to debug-request, current mode: Thread
xPSR: 0xf9000000 pc: 0x00000088 msp: 0xf0000000
[rp2350.cm1] halted due to debug-request, current mode: Thread
xPSR: 0xf9000000 pc: 0x00000088 msp: 0xf0000000
available
available
(gdb) b main
Breakpoint 1 at 0x100001ee: file apps/blinky/main.cc, line 25.
Note: automatically using hardware breakpoints for read-only addresses.
(gdb) c
Continuing.

Thread 1 "rp2350.cm0" hit Breakpoint 1, main () at apps/blinky/main.cc:25
25        sense::system::Init();
(gdb)

You can find more information in the “Getting started with Raspberry Pi Pico-series” documentation provided by the Raspberry Pi Foundation. In particular, “Appendix A: Debugprobe” covers OpenOCD and debugging.