Lis2duxs12 Qvar - touch ucf and power consumption questions

[Shannon Pahl]

1. Is there a ucf file or setup description for touch or swipe ? 

2. The power consumption seems very high for touch and swipe. Using the adapter board and Unico, with just the accelerometer and qvar running at 200hz low power mode, its about 13uA. I can see the qvar data plot working correctly but without the configuration of the mlc or fsm for touch. However, when touch is configured using the "Set Touch Detection Configuration' button, its running at about 52uA for touch and about 36uA for swipe. Does the mlc and fsm really use that much power for touch? Or are there some issues with the ST dev board in this scenario? Would setting the mlc odr lower help ? (but I'd need a way to reconfigure the mlc config, hence the need for the ucf or description)

[Federica Bossi · Accepted solution]

Hi @Shannon Pahl ,

1. Take a look at our examples on Github.

2. I confirm you that the consumption you see are correct, you can try to set a lower ODR, you can try and see if it is ok for you.

If my reply answered your question, please click on Accept as Solution at the bottom of this post. This will help other users with the same issue to find the answer faster :) 

[Shannon Pahl]

Thanks for the reply. But those examples do not refer to the qvar touch setup which is what I'm looking for.

[Shannon Pahl]

The touch events are detected with the FSM. Reducing the FSM ODR configuration to 100hz (vs 200), reduces the power to about 28uA total, so the component values are about (10uA, 3uA, 15uA) for (accel, qvar, FSM). So, if you have to run the accel anyways, adding in touch adds about 18uA at 100hz. You can save about 4uA if you can run the FSM at 50Hz.