MEMS-Studio FSM on MKI109D

Luisa_97 · ‎2025-05-11

Hi,

I have the STEVAL-MKI109D board, on which I mounted the STEVAL-MKI250KA. I would like to implement the free-fall example on the FSM, using data from the ST1VAFE3BX biosensor, using only MEMS Studio. Is it possible to do this without writing firmware solution? If so, how should I proceed?

Thanks.

casadeib · ‎2025-05-16

Hi @Luisa_97 ,

You can refer to the document AN6207 , in the paragraph 11.3 ("Examples of state machine configurations - Free Fall"). Here you can find the configuration that has to be implemented in the state machine.
The user has to set the commands in the green section (the final section of the table from 0Dh up to 19h) and the parameters of the variable data section in yellow (from 06h up to 0Ch), while the fixed data section (light blue - 00h up to 05h) is automatically managed by MEMS Studio. After writing the configuration to the device, it is possible to test the configuration using the dedicated tab.
Hope this could help. Please let me know if something is not clear to you.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

View solution in original post

casadeib · ‎2025-05-16

Hi @Luisa_97 ,

You can refer to the document AN6207 , in the paragraph 11.3 ("Examples of state machine configurations - Free Fall"). Here you can find the configuration that has to be implemented in the state machine.
The user has to set the commands in the green section (the final section of the table from 0Dh up to 19h) and the parameters of the variable data section in yellow (from 06h up to 0Ch), while the fixed data section (light blue - 00h up to 05h) is automatically managed by MEMS Studio. After writing the configuration to the device, it is possible to test the configuration using the dedicated tab.
Hope this could help. Please let me know if something is not clear to you.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

Luisa_97 · ‎2025-05-16

I have tested the free-fall configuration provided in document AN6207, but the results do not match my expectations. Could you help me identify where the issue might be?
My goal is to configure the FSM to generate an interrupt when the signal from the ST1VAFE3BX sensor exceeds a defined threshold.
More specifically, I would like the FSM to trigger an interrupt upon detection of a heartbeat event.

casadeib · ‎2025-05-20

Hi @Luisa_97

We reviewed your Freefall configuration and we identified a wrong timer configuration since it is currently configured to wait 0 samples , that is different from what is suggested in the Application Note (3 samples (03h), see Timer 3 variable section parameter at address 0Bh).

Moreover in order to identify such event what we suggest is to use the vAFE signal as input, instead of the accelerometer one.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

Luisa_97 · ‎2025-05-24

Hi @casadeib ,

Can you explain to me exactly what I need to configure in order to use the vAFE signal as input instead of the accelerometer?

Thanks.