Unreliable Uarte between the nRF9160DK and the nRF52840DK

[Christopher Hunt]

Hi there,

I'm trying to wire up a Uarte client to a Uarte server where the client device is an nRF9160DK, and the server is an nRF52840DK.

Connectivity between the cilent and server is unreliable. I've tried a manner of things including the enablement of the external HF clock on both boards. I've also tried a variety of baud rates. The configuration of the Uarte appears to be the same across both boards.

If I use a micro:bit v2 as the client instead of the nRF9160DK with the same firmware then all is well.

I'm wondering if the board controller function of the nRF9160DK (the 52840) is affecting communications in some way. I'm using P0_10 as the tx, and P0_12 as the rx. There is no hardware flow control as the firmware is destined for RS-485. This is a brand new nRF9160DK and so I'm presumably using the default board controller firmware on the 52840.

FYI I'm not using the Nordic SDK. There is more background here for any interest: github.com/.../553

Thanks so much for any pointers as I've spent days on this now!

[Vidar Berg]

Hello,

Please verify that you have the same IO voltage on both sides of the connection. The IO voltage on the 9160DK is 1.8v by default (see VDD supply rail for changing the IO voltage) whereas the nRF52840 DK has 3 volts when  supplied through the main USB port. I would expect the communication to be unreliable at best if the voltages don't match.

The pins you have selected should be available by default according to the nRF9160 DK board control table.

Best regards,

Vidar