Hello all,
I am having an issue with single-click detection. I am getting false click detections at certain threshold values. I found this out yesterday when I had an MCU register lots of clicks repeatedly, but the device was not being shaken.
To test, I set up the LIS2DH as follows (using I2C):
- Reset chip (write CTRL_REG5 with 0x80)
- Read WHOAMI until it returns 0x33 to make sure it's up
- Disable ODR and enable all 3 axes (write CTRL_REG1 with 0x07)
- Write CTRL_REG2 with 0x00 (just to be sure)
- Send Click to INT1 pin (write CTRL_REG3 with 0x80)
- Set BDU so I can read values, +/-2g, normal mode (write CTRL_REG4 with 0x80)
- Set up temperature (write TEMP_CFG_REG with 0xC0)
- Run Self test (Sets ODR to max, sets SELF_TEST_0, sets back to normal, test passes)
-
- Enable click interrupts on all 3 axes (write CLICK_CFG_REG with 0b010101)
- write CTRL_REG5 to 0x0
- Set ODR to 10Hz (write CTRL_REG1,4 accordingly)
- Set click threshold to 80
- Set click timeout to 127 (I leave it here always)
Now LIS2DH is set up at 10Hz ODR, with INT1 triggering on click and driving INT1 line high. Then I have a polling function that changes the CLICK_THS value every 5 seconds, and normal polling (more frequently) that watches for INT1 interrupts.
The 5-second poll increments CLICK_THS value up to 127, then sets it to 0 and sets ODR to disabled, then sets to 1 and ODR back to 10Hz, then increments CLICK_THS every 5 seconds from 1 to 127 again.
I have tested 4 devices so far (our manufactured devices with LIS2DH accel onboard. Each one detects false clicks at certain values of CLICK_THS:
- one board at 3, 4,16,17, 59, 60
- Second board at 2, 3, 10, 11, 65, 66
- Third board at 1, 2, 11, 12, 65
- Fourth board at 13, 33, 56
Has anyone seen anything like this before?
All these boards were tested sitting on my desk, with no actual bumping/clicking going on. Also, if there is an actual bump, they will detect it at all but the highest thresholds.
