nRF9160 COEX interface to nRF52840

[Avgerinos89]

Hello

I am building a hardware that requires to use the nRF9160 together with the nRF52840, in order to add the 2.4GHz radio support to the system and also to be able to perform a remote firmware update on the nRF52840 through the nRF9160.

Looking at the schematics of the nRF9160-DK I can see that there is an interface between the nRF9160 and the nRF52840 that uses 10 pins between the two chips.
The following pictures is a screenshot of the schematic showing the nRF9160 pins that are connected to the nRF9160.

On my board I do not have access to the COEX0, COEX1, COEX2 pins of the nRF9160, because I am using a module for the nRF9160 that does not provide access to these pins. My question is that, are these COEX pins required to be connected to the nRF52840?

Also, since I would like to use the 2.4GHZ ESB protocol that can run on the nRF52840, would it be possible with this hardware setup to do such thing?

And, finally as I understand it is possible to perform a remote firmware update on the nRF52840, via the nRF9160, using these hardware connections. Is this right?

Thanks in advance

[Sigurd Hellesvik]

Hi,

See nRF9160 design guidelines: COEX.

My question is that, are these COEX pins required to be connected to the nRF52840?

I will look into this.

Also, since I would like to use the 2.4GHZ ESB protocol that can run on the nRF52840, would it be possible with this hardware setup to do such thing?

If we for a moment assume that the COEX pins are not required, I see no problem with running ESB on the nRF52840 alongside the nRF9160.

And, finally as I understand it is possible to perform a remote firmware update on the nRF52840, via the nRF9160, using these hardware connections. Is this right?

Yes. See this for a sample.

Regards,
Sigurd Hellesvik

[Sigurd Hellesvik]

My question is that, are these COEX pins required to be connected to the nRF52840?

The Bluetooth LE and the LTE frequencies are very different, so I think there is a good chance that you will be fine without the COEX. The radios will still have an impact on each other, so you have to expect higher package loss than if you had COEX, but I can not tell exactly how large this will be.

I recommend that you test this with Development Kits to be sure.