Thingy91 Two UART Connections

[joebambino]

Hi Nordic,

Aquick question with respect to the Thingy91.  As part of our development, I am looking to the Thingy91 as a reference. In the Thingy91 design, it appears that the nRF9160 and the nRF52840 have two (2) UART connections between them.  It appears that the first (UART0) is running at 115200 baud and the second (UART1) is running at 1000000  baud. I am unclear as to why there are two separate UARTS and what purpose each serves.  Is it advisable to use only a single UART between the nRF9160 and the nRF5280 in order to free up a UART for other uses?

Thanks!

[Albrecht Markus Schellenberger]

Hello Joe,

It appears that the first (UART0) is running at 115200 baud and the second (UART1) is running at 1000000  baud

Yes, that is correct! But the baud-rates can of course be modified via a devicetree overlay.

In general, UART0 is used for console logging while UART1 is used for modem tracing on the nRF9160 side. But as you can see on the Thingy:91 pin map, the UART0/UART1 pins (P0.18 - P0.25) are considered as MCU_IF for communication with the nRF52840 as well.

For more information, you can download the Thingy:91 hardware files and check the file ../PCA20035-Thingy91 Board 1_6_0/Schematic_Layout pdf files/ PCA20035_Schematic_And_PCB.pdf.

Is it advisable to use only a single UART between the nRF9160 and the nRF5280 in order to free up a UART for other uses?

In general, peripherals are shared via memory instantiation, which makes it dependent on the design and purpose of your application. But you can of course use all the UART peripherals available.

I hope this will help you! Let me know if you have any more questions.

Regards,

Markus