RP2040-Zero RGB LED Project

This project drives the onboard WS2812 RGB LED on the Waveshare RP2040-Zero using the Raspberry Pi Pico SDK. The LED cycles through colors (Rainbow effect) with a period of approximately 1 minute.

Features

• Smooth Color Cycling: Uses floating-point HSV to RGB conversion for seamless color transitions.
• High Refresh Rate: Updates the LED at 100Hz (every 10ms) for fluid animation.
• Precise Timing: Uses RP2040's PIO (Programmable I/O) block to drive WS2812 timing, ensuring stability independent of CPU load.
• Bright Colors: Saturation and Value are set to maximum for vivid output.

Prerequisites

To build this project, you need the following installed on your system:

1. Raspberry Pi Pico SDK: The build system will attempt to download it automatically if not found.
2. CMake: Build system generator.
3. ARM GCC Toolchain: Compiler for the RP2040 (arm-none-eabi-gcc).
   • On macOS with Homebrew: brew install --cask gcc-arm-embedded

Building

1. Create a build directory:

   mkdir build
   cd build

2. Configure the project (this will download the SDK if needed):

   cmake .. -DPICO_SDK_FETCH_FROM_GIT=ON

3. Compile:

   make

Flashing

1. Hold the BOOT button on the RP2040-Zero while plugging it into USB (or press RESET while holding BOOT).
2. The board will appear as a mass storage device named RPI-RP2.
3. Drag and drop the generated rp2040_zero_led.uf2 file from the build directory onto the RPI-RP2 drive.

Project Structure

• main.c: Main application logic containing the HSV color conversion and animation loop.
• ws2812.pio: PIO assembly program handling the strict timing requirements of the WS2812 LED protocol.
• CMakeLists.txt: Build configuration for the Pico SDK.