Use Pigweed modules in your project#

If you’re integrating Pigweed into an existing project using Bazel, you can get started on this as soon as you’ve completed Set up Pigweed as an external dependency.

Let’s say you want to use pw::Vector from pw_containers, our embedded-friendly replacement for std::vector.

  1. Include the header you want in your code:

    #include "pw_containers/vector.h"

  2. Look at the module’s build file to figure out which build target you need to provide the header and implementation. For pw_containers/vector.h, it’s //pw_containers:vector.

  3. Add this target to the deps of your cc_library or cc_binary:

    cc_library(
    name = "my_library",
    srcs  = ["my_library.cc"],
    hdrs = ["my_library.h"],
    deps = [
        "@pigweed//pw_containers:vector",  # <-- The new dependency
    ],
)

  4. Add a dependency on @pigweed//pw_build:default_link_extra_lib to your final binary target. See Libraries required at linktime for a discussion of why this is necessary, and what the alternatives are.

    cc_binary(
    name = "my_binary",
    srcs  = ["my_binary.cc"],
    deps = [
        ":my_library",
        "@pigweed//pw_build:default_link_extra_lib",  # <-- The new dependency
    ],
)

Configure backends for facades you depend on#

Pigweed makes extensive use of Facades & backends, and any module you choose to use will likely have a transitive dependency on some facade (typically pw_assert or pw_log). Continuing with our example, pw::Vector depends on pw_assert.

In Bazel, facades already have a default backend (implementation) that works for host builds (builds targeting your local development machine). But to build a binary for your embedded target, you’ll need to select a suitable backend yourself.

Fortunately, the default backend for pw_assert is pw_assert_basic, which is a suitable place to start for most embedded targets, too. But it depends on pw_sys_io, another facade for which you will have to choose a backend yourself.

The simplest way to do so is to set the corresponding label flag when invoking Bazel. For example, to use the pw_sys_io_baremetal_stm32f429 backend for pw_sys_io provided in upstream Pigweed:

$ bazel build \
    --@pigweed//targets/pw_sys_io_backend=@pigweed//pw_sys_io_baremetal_stm32f429 \
    //path/to/your:target

You can also define backends within your own project. (If Pigweed doesn’t include a pw_sys_io backend suitable for your embedded platform, that’s what you should do now.) See Facades and backends tutorial for a tutorial that dives deeper into facade configuration with Bazel.

Next steps#

To ensure the correctness of your project’s code, set up Static and runtime analysis.

On this page