ADXL345 STM32 HAL Driver

A lightweight STM32 HAL-based driver for the ADXL345 3-axis digital accelerometer using the I2C interface.

This library provides basic device initialization, range and data rate configuration, raw acceleration reading, g-unit conversion, roll/pitch angle calculation, and basic offset calibration. You can access the datasheet from here.

Features

STM32 HAL I2C support
Device ID verification
Standby and measurement mode control
Selectable measurement range:
- ±2g
- ±4g
- ±8g
- ±16g
Selectable output data rate
Raw X/Y/Z acceleration reading
Acceleration conversion to g units
Roll and pitch angle calculation
Manual offset read/write
Basic automatic offset calibration
Simple handle-based driver structure

Hardware

This library is designed for the ADXL345 digital accelerometer connected to an STM32 microcontroller over I2C.

ADXL345 I2C Address Options

The ADXL345 has two possible I2C addresses depending on the state of the SDO/ALT ADDRESS pin.

SDO/ALT ADDRESS Pin	7-bit I2C Address	STM32 HAL Address
GND	`0x53`	`0xA6`
VDD	`0x1D`	`0x3A`

In this library, the STM32 HAL-compatible shifted addresses are defined as:

#define ADXL345_ADDRESS_LOW   (0x53 << 1)
#define ADXL345_ADDRESS_HIGH  (0x1D << 1)

Pin Connection

Example wiring for STM32 I2C usage:

ADXL345 Pin	STM32 Connection
VCC	3.3V
GND	GND
SDA	I2C SDA
SCL	I2C SCL
CS	3.3V
SDO/ALT ADDRESS	GND or 3.3V

CS must be connected to 3.3V for I2C mode.

Files

adxl345.h
adxl345.c

Public API

Initialization and Device Check

ADXL345_Status_t ADXL345_Init(
    ADXL345_Handle_t *dev,
    I2C_HandleTypeDef *hi2c,
    uint16_t address
);

Initializes the ADXL345 driver, verifies the device ID, configures the default settings, and enables measurement mode.

Default configuration:

Setting	Default Value
Range	±4g
Full-resolution mode	Disabled
Output data rate	100 Hz
Low-power mode	Disabled
Mode	Measurement mode

ADXL345_Status_t ADXL345_IsDeviceReady(ADXL345_Handle_t *dev);
ADXL345_Status_t ADXL345_ReadDeviceID(ADXL345_Handle_t *dev, uint8_t *deviceID);

Power Mode Control

ADXL345_Status_t ADXL345_SetStandbyMode(ADXL345_Handle_t *dev);
ADXL345_Status_t ADXL345_SetMeasureMode(ADXL345_Handle_t *dev);

The device can be placed into standby mode before configuration and then switched back to measurement mode.

Range Configuration

ADXL345_Status_t ADXL345_SetRange(
    ADXL345_Handle_t *dev,
    uint8_t range,
    uint8_t fullResolution
);

Supported range values:

ADXL345_RANGE_2G
ADXL345_RANGE_4G
ADXL345_RANGE_8G
ADXL345_RANGE_16G

Example:

ADXL345_SetRange(&adxl345, ADXL345_RANGE_4G, 0);

If fullResolution is set to 1, full-resolution mode is enabled.

Output Data Rate Configuration

ADXL345_Status_t ADXL345_SetDataRate(
    ADXL345_Handle_t *dev,
    uint8_t dataRate,
    uint8_t lowPower
);

Example:

ADXL345_SetDataRate(&adxl345, ADXL345_DATARATE_100HZ, 0);

Available data rate macros:

ADXL345_DATARATE_3200HZ
ADXL345_DATARATE_1600HZ
ADXL345_DATARATE_800HZ
ADXL345_DATARATE_400HZ
ADXL345_DATARATE_200HZ
ADXL345_DATARATE_100HZ
ADXL345_DATARATE_50HZ
ADXL345_DATARATE_25HZ
ADXL345_DATARATE_12_5HZ
ADXL345_DATARATE_6_25HZ
ADXL345_DATARATE_3_13HZ
ADXL345_DATARATE_1_56HZ
ADXL345_DATARATE_0_78HZ
ADXL345_DATARATE_0_39HZ
ADXL345_DATARATE_0_20HZ
ADXL345_DATARATE_0_10HZ

Raw Acceleration Reading

ADXL345_Status_t ADXL345_ReadRawXYZ(
    ADXL345_Handle_t *dev,
    ADXL345_RawData_t *rawData
);

Example:

ADXL345_RawData_t rawData;

if (ADXL345_ReadRawXYZ(&adxl345, &rawData) == ADXL345_OK) {
    // rawData.x
    // rawData.y
    // rawData.z
}

Acceleration Reading in g

ADXL345_Status_t ADXL345_ReadGXYZ(
    ADXL345_Handle_t *dev,
    ADXL345_GData_t *gData
);

Example:

ADXL345_GData_t gData;

if (ADXL345_ReadGXYZ(&adxl345, &gData) == ADXL345_OK) {
    // gData.x
    // gData.y
    // gData.z
}

Roll and Pitch Calculation

ADXL345_Status_t ADXL345_CalculateRollPitch(
    ADXL345_Handle_t *dev,
    ADXL345_Angle_t *angle
);

Example:

ADXL345_Angle_t angle;

if (ADXL345_CalculateRollPitch(&adxl345, &angle) == ADXL345_OK) {
    // angle.roll
    // angle.pitch
}

Roll and pitch calculation is based on gravity direction. It is suitable for static or slow-moving tilt sensing. Fast motion, vibration, or shock may distort the calculated angle values.

Offset Calibration

Manual offset write:

ADXL345_Status_t ADXL345_SetOffset(
    ADXL345_Handle_t *dev,
    int8_t xOffset,
    int8_t yOffset,
    int8_t zOffset
);

Offset read:

ADXL345_Status_t ADXL345_GetOffset(
    ADXL345_Handle_t *dev,
    int8_t *xOffset,
    int8_t *yOffset,
    int8_t *zOffset
);

Basic automatic calibration:

ADXL345_Status_t ADXL345_Calibrate(
    ADXL345_Handle_t *dev,
    uint16_t sampleCount
);

The calibration function assumes that the sensor is placed flat and stationary.

Expected acceleration during calibration:

X = 0g
Y = 0g
Z = +1g

Example:

ADXL345_Calibrate(&adxl345, 100);

Basic Usage Example

#include "adxl345.h"

ADXL345_Handle_t adxl345;
ADXL345_Status_t adxlStatus;

ADXL345_RawData_t rawData;
ADXL345_GData_t gData;
ADXL345_Angle_t angle;

int8_t offsetX = 0;
int8_t offsetY = 0;
int8_t offsetZ = 0;

int main(void)
{
    HAL_Init();

    /*
     * SystemClock_Config();
     * MX_GPIO_Init();
     * MX_I2C1_Init();
     */

    adxlStatus = ADXL345_Init(&adxl345, &hi2c1, ADXL345_ADDRESS_LOW);

    if (adxlStatus == ADXL345_OK) {
        ADXL345_Calibrate(&adxl345, 100);
        ADXL345_GetOffset(&adxl345, &offsetX, &offsetY, &offsetZ);
    }

    while (1) {
        if (ADXL345_ReadRawXYZ(&adxl345, &rawData) == ADXL345_OK) {
            /*
             * rawData.x
             * rawData.y
             * rawData.z
             */
        }

        if (ADXL345_ReadGXYZ(&adxl345, &gData) == ADXL345_OK) {
            /*
             * gData.x
             * gData.y
             * gData.z
             */
        }

        if (ADXL345_CalculateRollPitch(&adxl345, &angle) == ADXL345_OK) {
            /*
             * angle.roll
             * angle.pitch
             */
        }

        HAL_Delay(100);
    }
}

Data Structures

ADXL345 Handle

typedef struct {
    I2C_HandleTypeDef *hi2c;
    uint16_t address;
    uint8_t range;
    float scaleFactor;
} ADXL345_Handle_t;

Raw Data

typedef struct {
    int16_t x;
    int16_t y;
    int16_t z;
} ADXL345_RawData_t;

g Data

typedef struct {
    float x;
    float y;
    float z;
} ADXL345_GData_t;

Angle Data

typedef struct {
    float roll;
    float pitch;
} ADXL345_Angle_t;

Status Codes

typedef enum {
    ADXL345_OK = 0,
    ADXL345_ERROR,
    ADXL345_INVALID_ID,
    ADXL345_INVALID_PARAM
} ADXL345_Status_t;

Status	Description
`ADXL345_OK`	Operation completed successfully
`ADXL345_ERROR`	HAL communication or generic driver error
`ADXL345_INVALID_ID`	Device ID does not match the expected ADXL345 ID
`ADXL345_INVALID_PARAM`	Invalid function parameter

Notes

This library currently supports I2C communication.
STM32 HAL expects the ADXL345 I2C address to be shifted left by 1 bit.
The default initialization uses ±4g range and 100 Hz output data rate.
The calibration function assumes that the sensor is flat and stationary.
Roll and pitch values are reliable mainly for static or slow-moving tilt sensing.

Math Library Note

ADXL345_CalculateRollPitch() uses functions from math.h.

If you get a linker error such as:

undefined reference to `sqrt`

link the math library.

For GCC-based toolchains, add:

-lm

In STM32CubeIDE, this can usually be added from:

Project Properties
C/C++ Build
Settings
MCU GCC Linker
Libraries

Add:

Possible Future Improvements

Single tap and double tap detection
Activity and inactivity detection
Free-fall detection
Interrupt configuration
FIFO support
SPI support
Self-test function

License

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

Name		Name	Last commit message	Last commit date
.gitignore		.gitignore
LICENSE.txt		LICENSE.txt
README.md		README.md
adxl345.c		adxl345.c
adxl345.h		adxl345.h

Navigation Menu

Repository files navigation

ADXL345 STM32 HAL Driver

Features

Hardware

ADXL345 I2C Address Options

Pin Connection

Files

Public API

Initialization and Device Check

Power Mode Control

Range Configuration

Output Data Rate Configuration

Raw Acceleration Reading

Acceleration Reading in g

Roll and Pitch Calculation

Offset Calibration

Basic Usage Example

Data Structures

ADXL345 Handle

Raw Data

g Data

Angle Data

Status Codes

Notes

Math Library Note

Possible Future Improvements

License

About

Releases

Packages

Contributors

Languages

Latest commit

History

Folders and files

Repository files navigation

ADXL345 STM32 HAL Driver

Features

Hardware

ADXL345 I2C Address Options

Pin Connection

Files

Public API

Initialization and Device Check

Power Mode Control

Range Configuration

Output Data Rate Configuration

Raw Acceleration Reading

Acceleration Reading in g

Roll and Pitch Calculation

Offset Calibration

Basic Usage Example

Data Structures

ADXL345 Handle

Raw Data

g Data

Angle Data

Status Codes

Notes

Math Library Note

Possible Future Improvements

License

About

Topics

Resources

Stars

Watchers

Forks

Releases

Packages

Contributors

Languages