CAP1188 Sensitivity

[espruino-discuss2]

Posted at 2020-04-10 by SiFu

Hi there! :)
I recently bought some MDBT42 breakout boards and love them :)

Now I hooked up a Adafruit CAP1188 touch board to one of them and it works (with the https://www.espruino.com/CAP1188 module), but I would need to change the sensitivity of the board and I have no clue how to do that.

In Arduino this would work:
uint8_t reg = cap.readRegister( 0x1f ) & 0x0f;
cap.writeRegister( 0x1f, reg | 0x6F );

Can anyone point me to the right direction?
Thanks,
SiFu

[espruino-discuss2]

Posted at 2020-04-10 by Robin

Fri 2020.04.10

I have no experience with this specific module. Has the module source been reviewed?

https://www.espruino.com/modules/CAP1188.js

[espruino-discuss2]

Posted at 2020-04-12 by SiFu

Hi Robin,

thanks for your reply :)
I managed to get away with the default sensitivity, by rearranging the wiring even though it's all in a very tight space.

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[espruino-discuss2]

Posted at 2020-04-12 by @MaBecker

Nice, thanks for sharing.

Do you like to tell us what your project is about?

[espruino-discuss2]

Posted at 2020-04-12 by SiFu

Sure,
it's a BLE remote:
Previous, Play/Pause, Next, Volume Up and Volume Down

[espruino-discuss2]

Posted at 2020-04-12 by @MaBecker

Thanks for sharing, that's what I had in mind when I saw how you place the black circles.

Any information about the power consumption?

[espruino-discuss2]

Posted at 2020-04-14 by SiFu

According to the datasheet of the CAP1188 chip: "50uA quiescent current in Standby (1 sensor input monitored)". I will investigate more, if i find that the battery drains too fast.
But at least the cap1188 can send an interrupt, so that Espruino don't have to check the touch values continuously.
I definitely can recommend the cap1188! At first I implemented the remote with the touch pins of an ESP32, and that did not work very reliably

[espruino-discuss2]

Posted at 2020-04-14 by @MaBecker

But at least the cap1188 can send an interrupt

Yes, a setWatch() on an interrupt pin would be much more effective.

Did you had to create spirals at the cable ends or something similar, to make it more sensitivity?

[espruino-discuss2]

Posted at 2020-04-14 by Robin

Tue 2020.04.14

post #7 '50uA quiescent current in Standby'

As this is a nRf52, Just stumbled across this using Low Level PPI:

'Hardware capacitive sense on two pins'

search above string inside:

http://www.espruino.com/NRF52LL

[espruino-discuss2]

Posted at 2020-04-14 by SiFu

@mabe: No, the default sensitivity was too high with the way I originally had my wires. So I had to shorten some wires and bend others to have them apart as much as the limited space allows.

@robin: oh, nice! might try this one day. Would be curious if I could get that to work more reliable than the ESP32 touch pins I tried initially.
For now I'm pleased with the setup I have :)