ESP32-s3-MPU6050-SD-Logger

High-frequency IMU data logger for ESP32. Reads accelerometer and gyroscope data from an MPU6050 at 50 Hz and writes binary samples to an SD card using a FreeRTOS producer-consumer architecture.

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Overview

The firmware constantly samples 6-axis motion data and stores it to a binary file on an SD card. A producer task handles sensor reads every 20 ms, while a consumer task drains full data blocks from a queue and writes them to the filesystem. Data is periodically flushed to prevent loss on unexpected power cuts.

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Hardware Requirements

Component	Interface	Pins
ESP32-S3
MPU6050	I2C	SDA = 8, SCL = 9
SD card module	SPI	MOSI = 11, MISO = 13, CLK = 12, CS = 10

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Architecture

The firmware uses a double-buffering pattern built on two FreeRTOS queues:

• q_empty_buffers holds pre-allocated blocks waiting to be filled
• q_full_buffers holds completed blocks waiting to be written

Producer task runs at a fixed 50 Hz rate. It reads 14 bytes from the MPU6050 over I2C, parses accelerometer and gyroscope values from Big-Endian format, and stores each sample with a timestamp. Once a block reaches 100 samples, it is pushed to q_full_buffers.

Consumer task waits for full blocks and writes them to the SD card in a single fwrite call. Every 10 blocks, fflush and fsync are called to force a physical write to flash memory.

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Output Format

Data is written to /sdcard/imu_data.bin as a raw binary stream of imu_sample_t records.

typedef struct {
    uint32_t timestamp_ms;
    int16_t  accel_x;
    int16_t  accel_y;
    int16_t  accel_z;
    int16_t  gyro_x;
    int16_t  gyro_y;
    int16_t  gyro_z;
} imu_sample_t; // 16 bytes per record

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Build and Flash

This project is built with **ESP-IDF v5.5.2.

idf.py build
idf.py flash
idf.py monitor