LPComp events triggers by other inputs

RE: LPComp events triggers by other inputs

Aviv Okon — Tue, 25 Feb 2020 09:42:35 GMT

I tested this again, and the LPComp triggers correctly

I don't know how testing it on the wrong pins seemed to work correctly, but I guess I must have caused spikes in the currents of the ICs when I changed the voltage of the other pins

thank you for your help, feel free to close this case

RE: LPComp events triggers by other inputs

Aviv Okon — Tue, 25 Feb 2020 08:44:04 GMT

I found the issue

thanks to your comment, I realized that I had used the wrong pins (I took the pin number from the pca file instead of looking at the datasheet)

testing on the correct pins, it seems that everything is working properly

I'll test again to verify that the LPComp itself works correctly on the correct pins

not sure how changing the states of other pins generated the events, but I must have caused currents in the ICs and caused the issue

thanks a lot for your assistance, your test made me realize my error

after I've verified everything works, I'll let you know and close this

RE: LPComp events triggers by other inputs

Aviv Okon — Tue, 25 Feb 2020 08:03:45 GMT

thanks for the suggestion

currently the project is working on the nRF52840 evaluation board, so the circuit should be that of the evaluation board

if the issue is indeed caused by sudden changes to the ICs, it is either an issue with the two evaluation boards I have, or with the HW in general, though I hope it is something I did wrong in the code

I will keep your suggestions in mind and relay them to our HW team if we determine the issue is in fact HW related

RE: LPComp events triggers by other inputs

Jørgen Holmefjord — Mon, 24 Feb 2020 17:18:42 GMT

What do you have the LPCOMP pins connected to when you test this? I'm not able to generate the event when I have AIN0 connected to VDD and AIN1 connected to GND. When the pins are left unconnected/floating, I can see the event being generated many times, but I would expect the voltage level on floating pins bo to be affected by external circuitry.

I also tested with AIN0/AIN1 both connected to GND and both connected to VDD, not able to generate the events by pressing buttons.

RE: LPComp events triggers by other inputs

hmolesworth — Mon, 24 Feb 2020 15:36:24 GMT

You might consider ground bounce or Vdd dip; should the LPCOMP input level be near to the switching threshold, such bounce or dip occurring as a result of a change in applied load to Gnd and Vcc - such as turning an LED on or off - can push the sampled pin (actually maybe not the pin but internal circuit) to the threshold unexpectedly. A simple test is to run the same code and disconnect in turn anything that changes the current, typically the LEDs. If that changes the issue, then solutions involve signal routing, eg supply the LED from the battery but isolate the nRF via a schottcky or ideal diode with a local capacitor, or synchronously suppress the LPCOMP during LED transitions. Posting the circuit would allow more suggestions.

RE: LPComp events triggers by other inputs

Aviv Okon — Mon, 24 Feb 2020 13:17:04 GMT

devzone.nordicsemi.com/.../Sosense_5F00_POC.7z

what you are looking for is the sosense.emProject file (I recently ported to SES)

you may need to comment out some code, as it is expecting some peripherals, though it may work without any changes (please verify that nrf_drv_lpcomp_disable() is commented out in sosense_lpcomp_drv.c)

I noticed that in normal mode, pressing button 2 generates the event (I added the effect of LED 3 lighting for 0.5s when the event is sent)

In validation mode (press botton 1 when starting up), most actions generate the events (you can clearly see the prints by connecting with Tera Term or a similar program). you should see many logs of "LPComp High Voltage event". using the LED CLI command is easiest to test this

I hope this helps you test it, and please let me know if I can provide any more assistance, as it isn't a small project and is kind of messy (we're trying many things with it)

RE: LPComp events triggers by other inputs

Jørgen Holmefjord — Mon, 24 Feb 2020 10:06:12 GMT

Ok, these pins should not overlap with the analog inputs. You can upload a zipped version of the project as an attachment to your comment/answer here (Insert -> Insert image/video/file). If you do not want to post the code in public, I can convert the case into a private one.

RE: LPComp events triggers by other inputs

Aviv Okon — Sun, 23 Feb 2020 07:40:54 GMT

the LEDs trigger these events, and the LEDs are configured normally on the evaluation board (the BSP_LED_X GPIOs)

I can try to provide the full project, if there is some way to send it your way (it's currently in SES, though I doubt that would cause issues)

let me know which method would be most comfortable for you

RE: LPComp events triggers by other inputs

Jørgen Holmefjord — Thu, 20 Feb 2020 13:49:28 GMT

Hi,

Which GPIOs are you using for the other modules that trigger the events?

Can you provide a full project that can be used to reproduce this behavior?

Best regards,
Jørgen