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README.md
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# LIS3DH
A C89 driver for the 3-axis accelerometer LIS3DH. Supports both i2c and SPI.
A C89 driver for the 3-axis accelerometer LIS3DH. Supports both I2C and SPI.
> ### Features
### Features
> - FIFO
> - HP filter
> - 2G, 4G, 8G and 16G
> - Low-power mode, normal mode and high-resolution mode
> - ADC (x3) and temperature sensing
> - ADC and temperature sensing
> - Interrupt generation
> - Free-fall detection (soon)
> - Free-fall detection
> - Single-click detection
> - Double-click detection
> - 4D/6D orientation detection (soon)
## Examples
See the examples/ dir for complete code examples
See the `examples/` dir for complete code examples
## Implementation
This driver requires the user to provide pointers to the following abstractely named functions:
This driver requires the user to implement the following interface 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` */
/* 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 device register `reg` */
/* 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.
All above functions return `0` on success, and any non-zero value on error.
The `init` and `deinit` pointers can both be set to `NULL` and they won't be run.
If `init` and `deinit` are set to `NULL`, they will be ignored. Useful on microcontrollers.
---
### Using i2c on STM32
Simple example code
Example code because I couldn't previously find working examples.
```c
#define LIS3DH_I2C_ADDR 0x18

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example/README.md
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Basic example of how to use this device
### file: fifo.c
Instead of polling for every single [x y z] set, a FIFO with programmable capacity ("watermark") can be used, and then dumped into memory once full.
All FIFO readings use 10-bit resolution regardless of the mode set in `lis.cfg.mode`.
The watermark level can be adjusted to a value [0-31] by modifying the `lis.cfg.fifo.fth` property before calling `lis3dh_configure()`.
Instead of polling for every single [x y z] set, a FIFO with programmable capacity ("watermark") can be used, and then dumped into memory once full. All FIFO readings use 10-bit resolution regardless of the mode set in `lis.cfg.mode`. The watermark level can be adjusted to a value [0-31] by modifying the `lis.cfg.fifo.fth` property before calling `lis3dh_configure()`.
The LIS3DH can optionally apply a HP filter on the sample data. It can be used to greatly reduce the "DC acceleration" present.
### file: interrupts.c
This device supports two different interrupt "output pins," `INT1` and `INT2`. The appropriate flag must be set in either `cfg.pin1` or `cfg.pin2` and the interrupt source must be configured to trigger into `INT1` or `INT2`. This file contains example code that listens and receives an interrupt when the FIFO watermark is reached i.e. it is full.
This device supports two different interrupt "output pins," `INT1` and `INT2`. The appropriate flag must be set in either `cfg.pin1` or `cfg.pin2` and the interrupt source must be configured to trigger into `INT1` or `INT2`.
This file contains example code that listens and receives an interrupt when the FIFO watermark is reached i.e. it is full.
### file: single-click.c
@ -40,6 +38,8 @@ Enable and read built-in temperature sensor
### Inertial interrupts
There are two interrupt registers, `int1` and `int2` that can be configured for inertial interrupts. The config structs are identical and contain the fields: `zh`, `zl`, `yh`, `yl`, `xh`, `xl`, and more. `zh` stands for `Z_axis_high` and `zl` stands for `Z_axis_low`. If both are enabled, the device will generate an interrupt upon Z-axis acceleration exceeding `threshold`, or upon Z-axis acceleration reading at or below `-threshold` (in OR mode. Not possible in AND mode).
| aoi | en_6d | interrupt mode |
|-----|-------|-------------------------|
@ -65,8 +65,6 @@ An interrupt is generated when all of the configures axes are at or above the th
An interrupt is generated when the device is "stable" in a known direction. The interrupt is active as long as the direction is maintained.
There are two interrupt registers, `int1` and `int2` that can be configured for inertial interrupts. The config structs are identical and contain the fields: `zh`, `zl`, `yh`, `yl`, `xh`, `xl`, and more. `zh` stands for `Z_axis_high` and `zl` stands for `Z_axis_low`. If both are enabled, the device will generate an interrupt upon Z-axis acceleration exceeding `threshold`, or upon Z-axis acceleration reading at or below `-threshold` (in OR mode. Not possible in AND mode).
### file: inertial-wakeup.c
Inertial interrupt example in OR mode (easily changed to AND mode) with configurable axes, threshold and minimum acceleration duration.