MMA8652 Motion Counter

[tonilg]

Hi,

Some weeks ago I bought a develpment board with the mma8652 accelerometer. I want to implement a counter of motion events with the register FF_MT_COUNTER. For any reason, I can't read a different value than 0 and I don't know why. I left you my configuration registers.

F_SETUP= 0x80h

FF_MT_CFG=0xF8h

FF_MT_THS=0x85h

Thanks,

Toni

[TomasVaverka · Accepted solution]

Hi Toni,

There seems to be some misunderstanding. The FF_MT_COUNTER register does not count motion events. Using this FF_MT_COUNTER register you can set the debounce filtering time to filter out irregular or spurious events.

Capture 1.JPG

Note that the time step used for the debounce sample count depends on the ODR and oversampling mode (Normal, LPLN, HighRes, LP). For example, an ODR of 100Hz in Normal mode and an FF_MT_COUNT value of 10 would result in a minimum debounce response time of 100ms (10ms x 10 counts). 

Capture 2.JPG

Best regards,

Tomas

[tonilg]

Hi Tomas,

thanks for your answer. I misunderstood the register's function. I have one question, If a configure my accelerometre with this parameters, which is saved in the FIFO?

Best regards,

Toni

[TomasVaverka]

Hi Toni,

As I do not fully understand your question, I would recommend you taking a closer look at the AN4073 that describes the FIFO and its usage in details.

Best regards,

Tomas