4.8 KiB
lis3dh/example
file: simple.c
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 cfg.mode.
The watermark level can be adjusted to a value [1-32] (0 disables FIFO) by modifying the cfg.fifo.size property before calling lis3dh_configure().
The LIS3DH can optionally apply a HP filter on the sampling to reduce 'static acceleration' from the data.
Note: it seems that the highest data rate (ODR) possible using FIFO is 200 Hz, faster than that and it does not want to restart after 1 FIFO buffer. To sample faster, such as at the advertised 5 KHz rate, you have to use lis3dh_read() with LP mode.
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 overrun is reached i.e. it is full.
Note: pin1.wtm will NOT trigger if the FIFO size is 32 (default). Use pin1.overrun if you want an interrupt when the FIFO is full at full size (32.)
file: single-click.c
Set up single-click detection (no latching interrupt possible)
file: double-click.c
Set up double-click detection (no latching interrupt possible)
file: adc.c
Enable and read built-in ADCs.
- Input range: 800 mV to 1600 mV
- Resolution: 8-bit in LP mode, 10-bit in normal and in HR mode.
- Sampling frequency: same as ODR
file: temp.c
Enable and read built-in temperature sensor
- Operating range: -40 to 85°C
- Step size: ±1°C
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 |
|---|---|---|
| 0 | 0 | OR combination |
| 0 | 1 | 6d MOVEMENT recognition |
| 1 | 0 | AND combination |
| 1 | 1 | 6d POSITION recognition |
OR combination
An interrupt is generated when at least one of the configured axes is at or above the threshold level.
6D MOVEMENT recognition
An interrupt is generated when the device moves from a direction (known or unknown) to a different known direction. The interrupt is only active for 1/ODR.
AND combination
An interrupt is generated when all of the configures axes are at or above the threshold level.
6D POSITION recognition
An interrupt is generated when the device is "stable" in a known direction. The interrupt is active as long as the direction is maintained.
file: inertial-wakeup.c
Inertial interrupt example in OR mode (easily changed to AND mode) with configurable axes, threshold and minimum acceleration duration.
file: free-fall.c
Inertial interrupt example activating upon free-fall. It works by using an AND mode interrupt of all the negative axes and comparing them to a threshold value (in the case of negative axis the threshold is multiplied by -1), recommended to be at 350mg (for >30 ms) and activating when the experienced negative acceleration is greater (abs. sense) than the negative threshold.
file: 6d-movement.c
Inertial interrupt example, generates an interrupt when some acceleration, threshold is experienced on any configured axis for duration time. Supposedly the device knows what a "known" direction is.
file: 6d-position.c
Inertial interrupt example, the interrupt line is kept active so long as the device is stable (ie acceleration on configured axes does not exceed threshold for duration time).
4D detection
4D detection is a subset of 6D detection meant for detecting portrait/landscape screen rotations on mobile phones, etc. It functionally works the same as the 6D modes, except that detection along the Z-axis is disabled.
file: 4d-movement.c
Inertial interrupt example, generates an interrupt when some acceleration, threshold is experienced on any configured axis for duration time. Supposedly the device knows what a "known" direction is.
file: 4d-position.c
Inertial interrupt example, the interrupt line is kept active so long as the device is stable (ie acceleration on configured axes does not exceed threshold for duration time).