uart console not working when connecting the nrf9160 DK to the battery.

RE: uart console not working when connecting the nrf9160 DK to the battery.

J0sh1101 — Wed, 12 Jul 2023 08:40:05 GMT

Hi,

[quote userid="106736" url="~/f/nordic-q-a/101600/uart-console-not-working-when-connecting-the-nrf9160-dk-to-the-battery/435659"]I see that you only use one line forUART, which I assume is TX.[/quote]

Yes, that is correct.

[quote userid="106736" url="~/f/nordic-q-a/101600/uart-console-not-working-when-connecting-the-nrf9160-dk-to-the-battery/435659"]What do you connect the UART reader to?[/quote]

to the PC.

[quote userid="106736" url="~/f/nordic-q-a/101600/uart-console-not-working-when-connecting-the-nrf9160-dk-to-the-battery/435659"]Could it be that the USB connection provides ground to an eventual laptop that is no longer present when you use only power supply?[/quote]

Yes, you are right. I only realized after you said it that the reference to common ground was missing.

After I connected the two grounds, the UART reader worked again. Thanks!

RE: uart console not working when connecting the nrf9160 DK to the battery.

Sigurd Hellesvik — Tue, 11 Jul 2023 09:21:46 GMT

I see that you only use one line forUART, which I assume is TX.
What do you connect the UART reader to?
Could it be that the USB connection provides ground to an eventual laptop that is no longer present when you use only power supply?

In addition, can you measure GND and VDD on the DK Power Supply and USB, so we can see what the difference is?

RE: uart console not working when connecting the nrf9160 DK to the battery.

J0sh1101 — Tue, 11 Jul 2023 08:23:43 GMT

Hi,

I did what you said. I replaced the battery with the power supply, then removed the entire circuit and added only the power supply, and it still remained the same. No change.

I then came up with the idea of adding an LED toggle. The application toggled the LED even when it was powered from the external power supply, but the UART didn't work. Here is an image of it:

When I connected the USB micro to the J6 while it was powered by the power supply, then suddenly the UART was active again.

Is there a jumper or line I need to trim to make it work?

Is this reproduceable on your side or am I only one getting this?

Thanks for the help.

RE: uart console problem when connecting the nrf9160 DK to the battery.

Sigurd Hellesvik — Fri, 07 Jul 2023 09:08:42 GMT

Hi,

Can you try to use a bench power supply on the same voltage of the battery in place of the battery?

If that does not work, can you try to change the bench power supply to 3V (if that works for your other circuit)?

Regards,
Sigurd Hellesvik