lf-mpu6050

Lost + Found MPU6050 6-Axis Accelerometer/Gyroscope driver library for Raspberry Pi Pico C SDK.

🔌 Hardware Setup

Standard Pin Mapping:

• SDA: GP4 (Pico Pin 6)
• SCL: GP5 (Pico Pin 7)
• Bus: I2C0

📦 Usage

Add this package to your conanfile.txt or CMake setup.

CMake Integration

target_link_libraries(your_project PUBLIC lf-mpu6050)

Driver Instantiation

#include "lf_mpu6050.h"

lf_mpu6050_t mpu;

// Initialize with the power-on ranges (+/-2 g, +/-250 deg/s)
if (lf_mpu6050_init(&mpu, i2c0, LF_MPU6050_DEFAULT_I2C_ADDR)) {
    // Successfully initialized!
}

// Read telemetry
float accel[3], gyro[3], temp;
if (lf_mpu6050_read_data(&mpu, accel, gyro, &temp)) {
    printf("Accel: X=%.2f, Y=%.2f, Z=%.2f g\n", accel[0], accel[1], accel[2]);
    printf("Gyro: X=%.2f, Y=%.2f, Z=%.2f rad/s\n", gyro[0], gyro[1], gyro[2]);
    printf("Temp: %.2f C\n", temp);
}

⚙️ Choosing ranges

The power-on defaults are the narrowest ranges the part offers, which makes them a poor fit for anything that moves quickly:

• ±250 °/s is exceeded by a hand flick or an ordinary aircraft aileron roll. A clipped gyroscope silently under-reports rotation.
• ±2 g is exceeded by any real manoeuvre or a decent knock. A saturated accelerometer reads low, which is worse than reading obviously wrong: code that sanity-checks the vector magnitude against 1 g becomes more likely to accept the bad sample, not less.

So pick ranges explicitly:

lf_mpu6050_config_t cfg;
lf_mpu6050_config_defaults(&cfg);
cfg.gyro_range  = LF_MPU6050_GYRO_1000DPS;
cfg.accel_range = LF_MPU6050_ACCEL_8G;
cfg.dlpf        = LF_MPU6050_DLPF_44HZ;  // keep motor vibration out
cfg.sample_rate_div = 0;                 // 1 kHz output with the DLPF on

if (!lf_mpu6050_init_config(&mpu, i2c0, LF_MPU6050_DEFAULT_I2C_ADDR, &cfg)) {
    // sensor did not answer
}

lf_mpu6050_read_data() scales according to whichever ranges are configured, so nothing downstream changes when you widen them. The ranges can also be changed after init with lf_mpu6050_set_gyro_range(), lf_mpu6050_set_accel_range() and lf_mpu6050_set_dlpf().

Filtering

cfg.dlpf sets the on-chip low-pass. LF_MPU6050_DLPF_OFF gives the widest bandwidth and an 8 kHz internal rate; every other setting drops the internal rate to 1 kHz. Some filtering is usually wanted, especially near motors or propellers, because vibration that reaches a derivative term is amplified by it.

SI units

lf_mpu6050_read_data() reports acceleration in g but angular rate in rad/s, which is easy to trip over. lf_mpu6050_read_si() is identical except that acceleration comes back in m/s², so both outputs are SI:

float accel[3], gyro[3];   // m/s^2 and rad/s
lf_mpu6050_read_si(&mpu, accel, gyro, NULL);

Gyroscope calibration

// The device must be completely still: any motion during this is measured
// as bias and subtracted from every later reading.
lf_mpu6050_calibrate_gyro(&mpu, 500);   // ~500 ms

Bias is stored in raw counts, so it stays correct if you change the full-scale range afterwards. Only the gyroscope is calibrated — separating accelerometer bias from gravity needs a multi-orientation procedure that does not belong behind a single call.

Notes on initialization

lf_mpu6050_init_config() issues a device reset before configuring, then selects the gyroscope PLL as the clock source rather than the internal oscillator the part powers up with (the datasheet recommends this; it drifts less). The reset matters across a warm boot: without it the device keeps whatever registers the previous firmware left behind.

lf_mpu6050_init() is unchanged and still applies the power-on ranges, so existing code keeps working and reading identical values.

API

Function	Purpose
lf_mpu6050_config_defaults	Fill a config with the power-on defaults
lf_mpu6050_init	Initialize with the power-on ranges
lf_mpu6050_init_config	Initialize with explicit ranges, filter and rate
lf_mpu6050_set_gyro_range	Change the gyroscope range
lf_mpu6050_set_accel_range	Change the accelerometer range
lf_mpu6050_set_dlpf	Change the low-pass bandwidth
lf_mpu6050_ping	Check the device answers on the bus
lf_mpu6050_calibrate_gyro	Average the gyroscope zero offset
lf_mpu6050_read_raw	Raw register counts
lf_mpu6050_read_data	Scaled: g and rad/s
lf_mpu6050_read_si	Scaled: m/s² and rad/s