How to configure the COEX interface as input on nRF9160

RE: How to configure the COEX interface as input on nRF9160

Heidi — Tue, 10 Mar 2020 08:04:01 GMT

[quote user="psychogenic"]but please confirm that I did read the docs correctly and that, in theory, this will be possible through COEX0.[/quote]

Yes, you read the docs correctly.

[quote user="psychogenic"]As a PS, it would be really sweet if the docs would mention when a feature is coming soon rather than actually available.[/quote]

I completely agree and I'll try to get the documentation improved to reflect the current status of development.

RE: How to configure the COEX interface as input on nRF9160

psychogenic — Mon, 09 Mar 2020 16:47:42 GMT

All right, CFUN=20 is what the a-gps sample uses, so I'll stick with that.

As for BLE side controlling the LTE modem: ok, will work around this with software, but please confirm that I did read the docs correctly and that, in theory, this will be possible through COEX0. Is this so?

As a PS, it would be really sweet if the docs would mention when a feature is coming soon rather than actually available.

RE: How to configure the COEX interface as input on nRF9160

Heidi — Mon, 09 Mar 2020 16:42:30 GMT

Okay, so the suggested work-around is to use AT+CFUN=20 to suspend LTE and let GPS run.

However, it is not really necessary for the application to try to schedule the modem and GNSS. Modem firmware has a built-in scheduling system so that the GNSS tracker will run during PSM and eDRX (and even normal DRX) gaps. Of course, to find a (cold start) fix a longer continuous GNSS period is needed, eDRX/DRX cycle is usually not enough for that.

Regarding LTE vs BLE, the BLE can avoid sending when COEX2 (automated signal from nRF91) is high. There is no way for BLE to suspend LTE modem via a signal to any COEX pin.

RE: How to configure the COEX interface as input on nRF9160

psychogenic — Mon, 09 Mar 2020 16:04:10 GMT

The current board has an nRF9160 and an nRF5340, and we intend to use the on-board GPS as well and perhaps some other radio stuff in future revisions.

So, in short, I've got an ORed logic where any active transmitter (including a GPIO from the '9160 to indicate when we're using GPS) drives the COEX0 line high and the hope was to leave the LTE alone and rely on coexistence to quiet the transmissions while any of the others want to be active.

RE: How to configure the COEX interface as input on nRF9160

Heidi — Mon, 09 Mar 2020 16:00:01 GMT

In theory yes, but what is the other transmitter you are using?

RE: How to configure the COEX interface as input on nRF9160

psychogenic — Mon, 09 Mar 2020 15:26:34 GMT

Oh, hum. Ok, so the workaround is to do it "manually"? I.e. tell the LTE to shutdown before operating other transmitters?

RE: How to configure the COEX interface as input on nRF9160

Heidi — Mon, 09 Mar 2020 15:22:54 GMT

Hi!

[quote user=""]Can COEX0 be used as an input from external devices to keep the LTE radio quiet?[/quote]

As of today, this functionality is unfortunately not implemented.

For now, you can only set this as an output, as per the AT command documentation you refer to AT%XCOEX0.

If you want more information on future roadmaps regarding this functionality, you can contact your regional sales manager. PM me your location and I can give you the contact information.

Best regards,

Heidi