LIS3DH

A C linux driver for the 3-axis accelerometer LIS3DH. Supports both I2C and SPI.

Features

• FIFO
• HP filter
• 2G, 4G, 8G and 16G
• Low-power mode, normal mode and high-resolution mode
• ADC and temperature sensing
• Interrupt generation
• Free-fall detection
• Single-click detection
• Double-click detection
• 4D/6D orientation detection
• Sleep-to-Wake/Return-to-Sleep
• Self test

Examples

See the example/ dir for complete code examples and explanations of LIS3DH terminology

Implementation

This driver requires the user to implement the following interface functions:

This project has example interface code for I2C and SPI used on Raspberry Pi 4 and STM32

/* initialise the "interface" */
int init(void);
/* read from register `reg', `size' amount of bytes, and write them to `dst' */
int read(uint8_t reg, uint8_t *dst, uint32_t size);
/* write `value' to register `reg' */
int write(uint8_t reg, uint8_t value);
/* sleep for `dur_us' microseconds */
int sleep(uint32_t dur_us);
/* deinitalise the "interface" */
int deinit(void);

All above functions return 0 on success, and any non-zero value on error.

If init and/or deinit are set to NULL, they will be ignored. Useful on microcontrollers.

---

Functions

int lis3dh_init(lis3dh_t *lis3dh);
int lis3dh_deinit(lis3dh_t *lis3dh);
int lis3dh_configure(lis3dh_t *lis3dh);
int lis3dh_read(lis3dh_t *lis3dh);
int lis3dh_read_fifo(lis3dh_t *lis3dh, struct lis3dh_fifo_data *fifo);
int lis3dh_read_int1(lis3dh_t *lis3dh);
int lis3dh_read_int2(lis3dh_t *lis3dh);
int lis3dh_read_click(lis3dh_t *lis3dh);
int lis3dh_reference(lis3dh_t *lis3dh);
int lis3dh_reset(lis3dh_t *lis3dh);
int lis3dh_read_adc(lis3dh_t *lis3dh);
int lis3dh_read_temp(lis3dh_t *lis3dh);
int lis3dh_fifo_reset(lis3dh_t *lis3dh);

All functions return 0 on success, and any non-zero value on error.

Raspberry Pi

First run $ sudo raspi-config and enable SPI and/or I2C.

Edit main.c to use I2C or SPI.

See i2c.c and spi.c for which pins/device to use.

$ git clone https://github.com/wrclark/lis3dh.git
$ cd lis3dh
$ make
$ ./lis3dh

STM32

I2C

#define LIS3DH_I2C_ADDR 0x18 /* can also be 0x19 */

int i2c_write(uint8_t reg, uint8_t value) {
    uint8_t buf[2] = { reg, value };
    HAL_I2C_Master_Transmit(&hi2c2, LIS3DH_I2C_ADDR << 1, buf, 2, HAL_MAX_DELAY);
    return 0;
}

int i2c_read(uint8_t reg, uint8_t *dst, uint32_t size) {
    if (size > 1) {
        reg |= 0x80; /* auto-increment bit */
    }
    uint8_t send[2] = { reg, 0x00 };
    HAL_I2C_Master_Transmit(&hi2c2, LIS3DH_I2C_ADDR << 1, send, 2, HAL_MAX_DELAY);
    HAL_I2C_Master_Receive(&hi2c2, LIS3DH_I2C_ADDR << 1, dst, size, HAL_MAX_DELAY);
    return 0;
}

SPI

CPHA=0 CPOL=0 8 bits motorola

/* Every sleep call duration is a multiple of 1000 us (1 ms) */
/* So dividing this value by 1000 is perfectly fine. */
int sleep_us(uint32_t dur_us) {``
    HAL_Delay(dur_us / 1000);
    return 0;
}

int spi_write(uint8_t reg, uint8_t value) {
    uint8_t send[2];

    reg &= 0x3F; /* clear 2 msbit */
    send[0] = reg;
    send[1] = value;

    /* CS LOW */
    HAL_GPIO_WritePin(SPI1_GPIO_CS_GPIO_Port, SPI1_GPIO_CS_Pin, GPIO_PIN_RESET);
    HAL_SPI_Transmit(&hspi1, send, 2, HAL_MAX_DELAY);
    /* CS HIGH */
    HAL_GPIO_WritePin(SPI1_GPIO_CS_GPIO_Port, SPI1_GPIO_CS_Pin, GPIO_PIN_SET);

    return 0;
}

int spi_read(uint8_t reg, uint8_t *dst, uint32_t size) {
    uint8_t send[2];
    reg |= 0x80; /* read bit = 1 */

    if (size > 1) {
        reg |= 0x40; /* auto increment for rx > 1 */
    }

    send[0] = reg;
    send[1] = 0x00;

    /* CS LOW */
    HAL_GPIO_WritePin(SPI1_GPIO_CS_GPIO_Port, SPI1_GPIO_CS_Pin, GPIO_PIN_RESET);
    HAL_SPI_Transmit(&hspi1, send, 2, 1000);
    HAL_SPI_Receive(&hspi1, dst, size, 1000);
    /* CS HIGH */
    HAL_GPIO_WritePin(SPI1_GPIO_CS_GPIO_Port, SPI1_GPIO_CS_Pin, GPIO_PIN_SET);

    return 0;
}