A lightweight C library for interfacing the STMicroelectronics LIS3MDL 3-axis magnetometer via I²C on the Raspberry Pi Pico (and other RP2040 boards) using the Pico C/C++ SDK.

• Features
• Hardware Requirements
• Software Requirements
• Getting Started
  • Cloning & Building
  • Wiring
• Usage
  • Initialization & Configuration
  • Reading Data
• API
• Example
• License
• Contributing

• I²C read/write helpers with timeout
• Automatic register address auto-increment for multi-byte reads
• Initialization/configuration of all LIS3MDL control registers
• Hard-iron offset & threshold setup
• Raw & calibrated (µT) axis data
• Heading (°) calculation
• On-chip temperature reading (°C)
• Status & interrupt‐source register decoding

• Raspberry Pi Pico (or any RP2040 board)
• LIS3MDL magnetometer breakout or module
• Pull-up resistors on SDA/SCL if not provided on your breakout

• Raspberry Pi Pico SDK (tested on v1.5.0+)
• CMake 3.13+
• A GCC toolchain for ARM Cortex-M0+

1. Clone the Pico project (or add as a submodule):

   git clone https://github.com/moeux/LIS3MDL.git cd LIS3MDL git submodule add https://github.com/moeux/LIS3MDL.git librares/LIS3MDL 

2. In your CMakeLists.txt, add:

   add_subdirectory(libraries/LIS3MDL) target_link_libraries(<your_executable> PRIVATE LIS3MDL) 

3. Build as usual

   mkdir build cd build cmake .. make 

#include "LIS3MDL.h" // Initialize I²C and LIS3MDL i2c_init(i2c0, 100 * 1000); gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C); gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C); gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN); gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN); if (!lis3mdl_init()) { printf("LIS3MDL init failed!\n"); return; } // Optional: calibrate offsets (hard-iron) lis3mdl_set_offsets(0, 0, 0); // Optional: set interrupt threshold lis3mdl_set_threshold(1000);

status_t st; axes_raw_data_t raw; axes_data_t data; int16_t temp_raw; // Poll for data-ready if (lis3mdl_read_status(&st) && st.data_available) { lis3mdl_read_raw_axes(&raw); data = lis3mdl_get_microteslas(raw, GAUSS_4); float heading = lis3mdl_get_heading(raw.x, raw.y); lis3mdl_read_raw_temperature(&temp_raw); float temperature = lis3mdl_get_celcius(temp_raw); printf("X: %.2f μT, Y: %.2f μT, Z: %.2f μT\n", data.x, data.y, data.z); printf("Heading: %.1f°\n", heading); printf("Temp: %.1f °C\n", temperature); }

(See header comments for full prototypes.)

See the main() in LIS3MDL.c for a complete demo:

• Turns the on-board LED on while initializing
• Prints raw & scaled axes, heading, and temperature every sample

This project is licensed under the MIT License. See LICENSE for details.

1. Fork the repo
2. Create a feature branch (git checkout -b feature/awesome)
3. Commit your changes
4. Open a Pull Request