Introduction

This crate provides a comprehensive template for developing Ada firmware for the RP2040 ARM 32-bit microcontroller, using the GNAT Predefined Embedded Runtime implemented by the embedded_rp2040 and rp2040_hal crates and their dependencies.

Ada firmware for a microcontroller is realized as a main program procedure that is called by otherwise invisible runtime startup code, exactly as C firmware is realized by a function main() that is called by otherwise invisible runtime startup code.

Post-Build Script

An Alire project directory created by alr get munts_rp2040_firmware_embedded will include a post-build script named postbuild.sh. This script will install the newly built firmware to a mounted RP2040 ROM boot USB file system. The RP2040 ROM boot code implements USB mass storage emulation, in a fashion first popularized by the late and lamented Mbed OS. To flash RP2040 firmware, you just assert BOOTSEL and RESET hardware signals to force the RP2040 into ROM boot mode, mount the USB mass storage device (usually done automatically by the development machine operating system), and then copy a UF2 firmware image file it. postbuild.sh uses the elf2uf2 utility program to copy the firmware image to the RP2040.

You can explicitly specify the RP2040 mount point aka destination directory with the RP2040_DESTDIR environment variable before running alr build. Otherwise postbuild.sh will search for the RP2040 mount point at expected locations for ChromeOS, Linux, macOS, and Microsoft Windows.

If an RP2040 mount point cannot be found, postbuild.sh does nothing.

Makefile

An Alire project directory created by alr get munts_rp2040_firmware_embedded will include an optional but useful GNU Makefile (also available at https://github.com/pmunts/alire-goodies) containing the following goals or targets:

• build – Accomplished by the command gmake build. Runs alr build to build the firmware image. Result (upon success) is a 32-bit ARM ELF executable file in the bin/ subdirectory.
• clean – Accomplished by the command gmake clean. Removes all generated working files. What is left will be suitable for checking into a source control system.
• distclean – Accomplished by the command gmake distclean. Removes all generated working files and removes Alire’s crate download and build caches.

Note: make is often a synonym (symbolic link, shell alias, etc.) for gmake on Linux machines, meaning that make build behaves exactly the same as gmake build.

Visual Studio Code

An Alire project directory created by alr get munts_rp2040_firmware_embedded will include an optional but useful .vscode/tasks.json (also available at https://github.com/pmunts/alire-goodies) which provides some build tasks for Visual Studio Code.

You can invoke a Visual Studio build task from the application menu Terminal => Run Task... or Terminal => Run Build Task...

The most straightforward way to build and install RP2040 firmware from within Visual Studio Code is to simply press CONTROL + SHIFT + B. This key code invokes the default build task which executes the command make clean build which executes the command alr build which executes script postbuild.sh.

Examples

Command line

alr -n get munts_rp2040_firmware_embedded
alire-rename munts_rp2040_firmware_embedded_2.24820.1_45796fc8 myfirmware  # optional
cd myfirmware
alr -n with munts_rp2040_lib_embedded  # optional
alr build

Visual Studio Code

alr -n get munts_rp2040_firmware_embedded
alire-rename munts_rp2040_firmware_embedded_2.24820.1_45796fc8 myfirmware  # optional
cd myfirmware
alr -n with munts_rp2040_lib_embedded  # optional
code .

Note: The Alire project rename script alire-rename is available at https://github.com/pmunts/alire-goodies.