Blinky_Pico_dual_core_nosdk

This repository implements an entirely manually-written, Blinky Project for the RaspberryPi(R) Pico RP2040 dual-core ARM(R) Cortex(R)-M0+ (RPI PICO RP2040). It exhibits pure bare metal programming on on the RaspberryPi(R) Pico RP2040 dual-core ARM(R) Cortex(R)-M0+ and uses no sdk.

Features include:

• CPU, dual-core, clock and PLL initialization,
• timebase derived from SysTick,
• blinky LED show on the green user LED on port25,
• implementation in C99 with absolute minimal use of assembly.

A clear and easy-to-understand build system based on GNUmake completes this fun and educational project.

This repository provides keen insight on starting up a bare metal RaspberryPi(R) Pico RP2040 dual-core ARM(R) Cortex(R)-M0+ controller using no sdk.

Details on the Application

The application boots from the secondary boot-loader (SBL) at the start location. This low-level startup boots through core 0. Core 0 then starts up core 1 (via a specific protocol). Core 1 subsequently carries out the blinky application, while core 0 enters an endless, idle loop.

Low-level initialization brings the CPU up to full speed at $133~MHz$. Hardware settings such as wait states have seemingly been set by the boot-loader.

The blinky LED show utilizes the green user LED on port25.

Building the Application

Build on *nix* is easy using an installed gcc-arm-none-eabi

cd Blinky_Pico_dual_core_nosdk
Rebuild.sh

The build results including ELF-file, HEX-mask, MAP-file and assembly list file are created in the Output directory.

If gcc-arm-none-eabi is not installed, it can easily be installed with

sudo apt install gcc-arm-none-eabi

Continuous Integration

CI runs on pushes and pull-requests with a simple build and result verification on ubuntu-latest using GutHub Actions.