Pico with C/C++

Pico with C/C++
Author

Benedict Thekkel

🧰 1. Prerequisites

Tool Purpose
VS Code Editor
CMake + Ninja Build system
pico-sdk Raspberry Pi official C/C++ SDK
arm-none-eabi GCC toolchain for ARM Cortex-M0+
OpenOCD Debugging (optional for SWD)
UF2 uploader Flashing firmware via USB (drag-and-drop or tools)

🧭 2. Pico SDK Workflow Overview

[ C Code ] β†’ [ CMake ] β†’ [ Ninja ] β†’ [ ELF/BIN/UF2 ] β†’ [ Raspberry Pi Pico ]

πŸ–₯️ 3. Install Toolchain on Linux (Ubuntu)

sudo apt update
sudo apt install cmake gcc-arm-none-eabi build-essential ninja-build libnewlib-arm-none-eabi git

On Windows/macOS: use Raspberry Pi Pico official getting started guide

πŸ“‚ 4. Project Structure

pico-project/
β”œβ”€β”€ CMakeLists.txt          # Top-level
β”œβ”€β”€ blink/
β”‚   β”œβ”€β”€ CMakeLists.txt
β”‚   └── blink.c
└── pico-sdk/               # Submodule or symlink to SDK

πŸ“„ 5. blink.c Example

#include "pico/stdlib.h"

int main() {
    const uint LED_PIN = 25;
    gpio_init(LED_PIN);
    gpio_set_dir(LED_PIN, GPIO_OUT);

    while (true) {
        gpio_put(LED_PIN, 1);
        sleep_ms(500);
        gpio_put(LED_PIN, 0);
        sleep_ms(500);
    }
}

βš™οΈ 6. blink/CMakeLists.txt

add_executable(blink
    blink.c
)

target_link_libraries(blink pico_stdlib)

pico_add_extra_outputs(blink)

🧱 7. Top-level CMakeLists.txt

cmake_minimum_required(VERSION 3.13)
include(pico-sdk/pico_sdk_init.cmake)

project(pico_project C CXX ASM)
pico_sdk_init()

add_subdirectory(blink)

πŸ”„ 8. Building the Project

# First-time setup
git clone -b master https://github.com/raspberrypi/pico-sdk.git
cd pico-sdk
git submodule update --init

# Back to project
cd ..
mkdir build && cd build
cmake .. -DPICO_SDK_PATH=../pico-sdk -G Ninja
ninja

You should see:

[100%] Built target blink

πŸš€ 9. Flash to Pico (UF2)

  • Hold BOOTSEL, plug in Pico β†’ it shows up as a USB drive
  • Copy blink.uf2 from build/ to that drive
cp blink.uf2 /media/YOUR_USER/RPI-RP2/

Or use picotool:

sudo apt install picotool
picotool load blink.uf2 -f

πŸ›  10. Set Up VS Code

Extensions to install:

  • C/C++ (by Microsoft)
  • CMake Tools
  • Cortex-Debug (if using SWD debugging)
  • CMake Tools Helper (optional)
  • CodeLLDB (optional for debugging with picoprobe)

.vscode/settings.json

{
  "cmake.generator": "Ninja",
  "cmake.configureSettings": {
    "PICO_SDK_PATH": "${workspaceFolder}/pico-sdk"
  },
  "C_Cpp.default.configurationProvider": "ms-vscode.cmake-tools"
}

.vscode/launch.json (for debugging via SWD)

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Cortex Debug",
      "type": "cortex-debug",
      "request": "launch",
      "servertype": "openocd",
      "executable": "build/blink.elf",
      "cwd": "${workspaceRoot}",
      "device": "RP2040",
      "configFiles": [
        "interface/picoprobe.cfg",
        "target/rp2040.cfg"
      ]
    }
  ]
}

πŸ§ͺ 11. Testing with Serial Output

Use USB UART (CDC) via USB connection.

stdio_init_all();  // Enables printf over USB

printf("Hello from Pico!\n");

Use:

screen /dev/ttyACM0 115200

or

picocom -b 115200 /dev/ttyACM0

🧠 12. Tips & Best Practices

Tip Description
Use pico_add_extra_outputs() Builds .uf2, .elf, .bin for flashing
Don’t forget pico_sdk_init() Required in top-level CMakeLists.txt
Use Git submodule for SDK Keeps SDK in sync with your project
Debug with SWD or USB CDC logging Debug via UART or SWD using picoprobe
Use build/ for all CMake outputs Keep source tree clean

πŸ“š Further Reading

βœ… Summary

Task Command / Tool
Build cmake .. && ninja
Flash (USB) Drag .uf2 to Pico drive
Debug (optional) picoprobe + OpenOCD
Serial Print Debugging stdio_init_all(), then picocom
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