466 lines
12 KiB
Markdown
466 lines
12 KiB
Markdown
# LIS3DH
|
|
|
|
A C89 driver for the 3-axis accelerometer LIS3DH. Supports both i2c and SPI.
|
|
|
|
> ### Features
|
|
> - FIFO of varying watermark level, up to 32
|
|
> - HP filter (4 c/o freq)
|
|
> - 2G, 4G, 8G and 16G
|
|
> - All power modes
|
|
> - Interrupt generation (partial)
|
|
> - Free-fall detection (soon)
|
|
> - Single and double click detection (soon)
|
|
> - 4D/6D orientation detection (soon)
|
|
|
|
## Implementation
|
|
This driver requires the user to provide pointers to the following abstractely named functions:
|
|
|
|
This project has example interface code for I2C used on Raspberry Pi.
|
|
```c
|
|
/* initialise the "interface" */
|
|
int init(void);
|
|
/* read from device 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 device 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.
|
|
|
|
## Usage
|
|
Simple example:
|
|
```c
|
|
#define _GNU_SOURCE
|
|
#include <unistd.h> /* usleep() */
|
|
#include <stdio.h>
|
|
#include "lis3dh.h"
|
|
#include "i2c.h"
|
|
|
|
int main() {
|
|
|
|
lis3dh_t lis;
|
|
|
|
lis.dev.init = i2c_init;
|
|
lis.dev.read = i2c_read;
|
|
lis.dev.write = i2c_write;
|
|
lis.dev.sleep = usleep;
|
|
lis.dev.deinit = i2c_deinit;
|
|
|
|
if (lis3dh_init(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
lis.cfg.mode = LIS3DH_MODE_HR;
|
|
lis.cfg.range = LIS3DH_FS_4G;
|
|
lis.cfg.rate = LIS3DH_ODR_100_HZ;
|
|
|
|
if (lis3dh_configure(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_poll(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_read(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
printf("x: %f, y: %f, z: %f\n", lis.acc.x, lis.acc.y, lis.acc.z);
|
|
|
|
if (lis3dh_deinit(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
```
|
|
The output should be something similar to this:
|
|
```
|
|
$ ./lis3dh
|
|
x: 0.540000, y: -0.882000, z: -0.100000
|
|
```
|
|
poll() and read() can be indefinitely looped for a constant data stream, like this:
|
|
```c
|
|
#define _GNU_SOURCE
|
|
#include <unistd.h>
|
|
#include <stdio.h>
|
|
#include "lis3dh.h"
|
|
#include "i2c.h"
|
|
|
|
int main() {
|
|
|
|
lis3dh_t lis;
|
|
int i;
|
|
|
|
lis.dev.init = i2c_init;
|
|
lis.dev.read = i2c_read;
|
|
lis.dev.write = i2c_write;
|
|
lis.dev.sleep = usleep;
|
|
lis.dev.deinit = i2c_deinit;
|
|
|
|
if (lis3dh_init(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
lis.cfg.mode = LIS3DH_MODE_HR;
|
|
lis.cfg.range = LIS3DH_FS_4G;
|
|
lis.cfg.rate = LIS3DH_ODR_100_HZ;
|
|
|
|
if (lis3dh_configure(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
for(i=0; i<10; i++) {
|
|
|
|
if (lis3dh_poll(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_read(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
printf("x: %f, y: %f, z: %f\n", lis.acc.x, lis.acc.y, lis.acc.z);
|
|
}
|
|
|
|
if (lis3dh_deinit(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
```
|
|
Output:
|
|
```
|
|
$ ./lis3dh
|
|
x: 0.534000, y: -0.882000, z: -0.102000
|
|
x: 0.538000, y: -0.866000, z: -0.136000
|
|
x: 0.518000, y: -0.846000, z: -0.100000
|
|
x: 0.518000, y: -0.840000, z: -0.098000
|
|
x: 0.542000, y: -0.876000, z: -0.098000
|
|
x: 0.518000, y: -0.834000, z: -0.146000
|
|
x: 0.512000, y: -0.854000, z: -0.106000
|
|
x: 0.574000, y: -0.870000, z: -0.122000
|
|
x: 0.518000, y: -0.846000, z: -0.098000
|
|
x: 0.516000, y: -0.852000, z: -0.112000
|
|
```
|
|
## Using FIFO
|
|
Instead of polling for every single [x y z] set, a FIFO with programmable capacity ("watermark") can be used like such:
|
|
|
|
All FIFO readings use 10-bit resolution regardless of the mode set in `lis.cfg.mode`.
|
|
The watermark level can also be adjusted to a value [0-31] inclusive by modifying the `lis.cfg.fifo.fth` property before calling configure().
|
|
```c
|
|
#define _GNU_SOURCE
|
|
#include <unistd.h>
|
|
#include <stdio.h>
|
|
#include "lis3dh.h"
|
|
#include "i2c.h"
|
|
|
|
int main() {
|
|
|
|
lis3dh_t lis;
|
|
struct lis3dh_fifo_data data;
|
|
int i;
|
|
|
|
lis.dev.init = i2c_init;
|
|
lis.dev.read = i2c_read;
|
|
lis.dev.write = i2c_write;
|
|
lis.dev.sleep = usleep;
|
|
lis.dev.deinit = i2c_deinit;
|
|
|
|
if (lis3dh_init(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
lis.cfg.mode = LIS3DH_MODE_HR;
|
|
lis.cfg.range = LIS3DH_FS_4G;
|
|
lis.cfg.rate = LIS3DH_ODR_100_HZ;
|
|
lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_NORMAL;
|
|
|
|
if (lis3dh_configure(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_poll_fifo(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_read_fifo(&lis, &data)) {
|
|
/* error handling */
|
|
}
|
|
|
|
/* read out fifo buffer data */
|
|
for(i=0; i<data.size; i++) {
|
|
printf("x: %f, y: %f, z: %f\n", data.x[i], data.y[i], data.z[i]);
|
|
}
|
|
|
|
if (lis3dh_deinit(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
```
|
|
Output:
|
|
```
|
|
$ ./lis3dh
|
|
x: 0.544000, y: -0.904000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.104000
|
|
x: 0.528000, y: -0.880000, z: -0.104000
|
|
x: 0.528000, y: -0.880000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.104000
|
|
x: 0.536000, y: -0.880000, z: -0.128000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.568000, y: -0.872000, z: -0.160000
|
|
x: 0.560000, y: -0.872000, z: -0.160000
|
|
```
|
|
## Using the HP filter
|
|
The LIS3DH can optionally apply a HP filter on the sample data. It can be used to greatly reduce the "DC acceleration" present.
|
|
```c
|
|
#define _GNU_SOURCE
|
|
#include <unistd.h>
|
|
#include <stdio.h>
|
|
#include "lis3dh.h"
|
|
#include "i2c.h"
|
|
|
|
int main() {
|
|
|
|
lis3dh_t lis;
|
|
struct lis3dh_fifo_data data;
|
|
int i;
|
|
|
|
lis.dev.init = i2c_init;
|
|
lis.dev.read = i2c_read;
|
|
lis.dev.write = i2c_write;
|
|
lis.dev.sleep = usleep;
|
|
lis.dev.deinit = i2c_deinit;
|
|
|
|
if (lis3dh_init(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
lis.cfg.mode = LIS3DH_MODE_HR;
|
|
lis.cfg.range = LIS3DH_FS_4G;
|
|
lis.cfg.rate = LIS3DH_ODR_100_HZ;
|
|
lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_NORMAL;
|
|
lis.cfg.filter.mode = LIS3DH_FILTER_MODE_AUTORESET;
|
|
lis.cfg.filter.cutoff = LIS3DH_FILTER_CUTOFF_8;
|
|
|
|
if (lis3dh_configure(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_poll_fifo(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_read_fifo(&lis, &data)) {
|
|
/* error handling */
|
|
}
|
|
|
|
/* read out fifo buffer data */
|
|
for(i=0; i<data.size; i++) {
|
|
printf("x: %f, y: %f, z: %f\n", data.x[i], data.y[i], data.z[i]);
|
|
}
|
|
|
|
if (lis3dh_deinit(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
```
|
|
Output:
|
|
```
|
|
$ ./lis3dh
|
|
x: 0.008000, y: 0.000000, z: 0.000000
|
|
x: 0.000000, y: 0.000000, z: 0.016000
|
|
x: -0.016000, y: -0.008000, z: -0.008000
|
|
x: -0.032000, y: 0.008000, z: 0.000000
|
|
x: 0.024000, y: -0.016000, z: -0.032000
|
|
x: 0.024000, y: -0.016000, z: -0.032000
|
|
x: 0.024000, y: -0.016000, z: -0.032000
|
|
x: 0.024000, y: -0.016000, z: -0.032000
|
|
x: 0.024000, y: -0.016000, z: -0.032000
|
|
x: 0.024000, y: -0.016000, z: -0.032000
|
|
x: 0.024000, y: -0.016000, z: -0.032000
|
|
x: 0.024000, y: -0.016000, z: -0.008000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.016000, y: -0.032000, z: -0.040000
|
|
x: -0.008000, y: -0.024000, z: -0.008000
|
|
```
|
|
## Using interrupts
|
|
|
|
The LIS3DH supports two different interrupt "output pins," `INT1` and `INT2`. The appropriate flag must be set in either `cfg.int1` or `cfg.int2` (only one of such flags can be set at a time!) and the interrupt source must be configured to trigger into `INT1` or `INT2`. Below is example code that listens and receives an interrupt when the FIFO watermark is reached i.e. it is full.
|
|
|
|
```c
|
|
#define _GNU_SOURCE
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <math.h>
|
|
#include "lis3dh.h"
|
|
#include "interrupt.h"
|
|
#include "i2c.h"
|
|
|
|
/* GPIO 12 or Pin 32 */
|
|
#define GPIO_INTERRUPT_PIN 12
|
|
|
|
int main() {
|
|
|
|
lis3dh_t lis;
|
|
struct lis3dh_fifo_data fifo;
|
|
int k;
|
|
|
|
lis.dev.init = i2c_init;
|
|
lis.dev.read = i2c_read;
|
|
lis.dev.write = i2c_write;
|
|
lis.dev.sleep = usleep;
|
|
lis.dev.deinit = i2c_deinit;
|
|
|
|
if (lis3dh_init(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
/* register interrupt */
|
|
if (int_register(GPIO_INTERRUPT_PIN)) {
|
|
/* error handling */
|
|
}
|
|
|
|
lis.cfg.mode = LIS3DH_MODE_NORMAL;
|
|
lis.cfg.range = LIS3DH_FS_2G;
|
|
lis.cfg.rate = LIS3DH_ODR_100_HZ;
|
|
lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_STREAM;
|
|
lis.cfg.fifo.trig = LIS3DH_FIFO_TRIG_INT1; /* trigger into INT1 */
|
|
lis.cfg.int1.wtm = 1; /* trigger upon watermark level reached */
|
|
|
|
if (lis3dh_configure(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
/* wait for interrupt from LIS3DH */
|
|
if (int_poll(GPIO_INTERRUPT_PIN)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_read_fifo(&lis, &fifo)) {
|
|
/* error handling */
|
|
}
|
|
|
|
for(k=0; k<fifo.size; k++) {
|
|
printf("%04.04f %04.04f %04.04f %04.04f\n", fifo.x[k], fifo.y[k], fifo.z[k]);
|
|
}
|
|
|
|
/* unregister interrupt */
|
|
if (int_unregister(GPIO_INTERRUPT_PIN)) {
|
|
/* error handling */
|
|
}
|
|
|
|
if (lis3dh_deinit(&lis)) {
|
|
/* error handling */
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
```
|
|
|
|
Output:
|
|
```
|
|
$ ./lis3dh
|
|
0.2040 -1.0120 -0.1720 1.0466
|
|
0.2200 -1.0200 -0.1600 1.0557
|
|
0.2160 -1.0200 -0.1600 1.0548
|
|
0.2120 -1.0240 -0.1600 1.0579
|
|
0.2200 -1.0160 -0.1760 1.0543
|
|
0.2080 -0.9960 -0.1720 1.0319
|
|
0.2080 -0.9960 -0.1760 1.0326
|
|
0.2200 -1.0200 -0.1600 1.0557
|
|
0.2200 -1.0160 -0.1560 1.0512
|
|
0.2160 -1.0200 -0.1600 1.0548
|
|
0.2120 -1.0240 -0.1520 1.0567
|
|
0.2200 -1.0240 -0.1520 1.0583
|
|
0.2160 -1.0200 -0.1520 1.0536
|
|
0.2160 -1.0200 -0.1560 1.0542
|
|
0.2080 -0.9960 -0.1760 1.0326
|
|
0.2200 -1.0240 -0.1600 1.0595
|
|
0.2120 -1.0000 -0.1720 1.0366
|
|
0.2120 -0.9960 -0.1760 1.0334
|
|
0.2200 -1.0240 -0.1600 1.0595
|
|
0.2200 -1.0200 -0.1600 1.0557
|
|
0.2080 -0.9960 -0.1640 1.0306
|
|
0.1920 -1.0080 -0.1600 1.0385
|
|
0.2080 -1.0080 -0.1600 1.0416
|
|
0.2200 -1.0240 -0.1520 1.0583
|
|
0.2080 -1.0000 -0.1720 1.0358
|
|
0.2080 -0.9960 -0.1480 1.0282
|
|
0.2040 -1.0240 -0.1560 1.0557
|
|
0.2200 -1.0240 -0.1560 1.0589
|
|
0.2120 -1.0040 -0.1520 1.0373
|
|
0.2120 -1.0200 -0.1560 1.0534
|
|
0.2200 -1.0240 -0.1560 1.0589
|
|
```
|
|
|
|
### Using i2c on STM32
|
|
Simple example code
|
|
```c
|
|
#define LIS3DH_I2C_ADDR 0x18
|
|
|
|
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) {
|
|
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;
|
|
}
|
|
```
|
|
|