I have configured the Wake-Up interrupt (with highpass filter) as described in the application note:
1. Write 60h to CTRL1_XL // Turn on the accelerometer // ODR_XL = 416 Hz, FS_XL = 2 g
2.Write 90h to TAP_CFG // Enable interrupts and apply high-pass digital filter; latched mode disabled
3.Write 00h to WAKE_UP_DUR // No duration
4.Write 02h to WAKE_UP_THS // Set wake-up threshold
5.Write 20h to MD1_CFG // Wake-up interrupt driven to INT1 pin
All other registers are used with default values.
After 2.6 ms of writing the MD1_CFG register the INT1 pin gets high and remains high 50 ms. I would expect, that the pin gets hight after a wake-up event occurs.. This case happens independently of the sampling frequency, wakeup trheshold or wakeup duration. After the 50 ms it seems to work fine.
I expect that the signal on INT1 is low until an wake-up event. Is this the normal behavior or or did I misconfigure something?