Thingy91 UART External communication

[Adeel]

Hi Dev Team,

I was working on the Nordic Thingy91 and had to establish an external communication of a sensor to the Thingy91 through a UART. 

For this, I was looking into the GPIO's to check which pins can be used for my Tx, Rx, CTS, RTS. 

I found this link : https://devzone.nordicsemi.com/f/nordic-q-a/64742/nordic-thingy-91-pin-name/264224#264224 that talked about using anything between P0.18-P0.25 (MCU_IF0-7).

https://github.com/nrfconnect/sdk-nrf/blob/master/boards/arm/thingy91_nrf9160/thingy91_nrf9160_common.dts#L165-L182

These are said to be connected to the nrf52840 interface. Can I just use these pins for my external UART connection ?

Also, I wanted to know the functions of these Test pads (TP). Can the test pads be also used for UART communication?

If so, how will it be defined in the thingy91_nrf9160_common.dts file. 

Regards,

Adeel.

[Adeel]

Hi,

After reading a bit about Test points (TP) and GPIO's, I am trying to use the following for my UART : 

Tx - TP32 / P0.13

Rx - TP33 / P0.16

RTS/CTS - TP7 / P0.10

Are there any other GPIO's that are free to be used ? 

Also, I wanted to understand the functionality of MCU_IF[0-7]. They are configured by default in the uart_config file. Will I loose any functionality if I try to use these pins for my external UART ?

Regards,

Adeel.

[JONATHAN LL]

Hi Adeel,


Link to Thingy 91 Test points table. Most of the TP are in use or not really accessible and are there for testing and debugging or connected to sensors in use, in the link you can see all the listed test points and there use on the Thingy91. 

Check out the following links for more information on previous attempts:
https://devzone.nordicsemi.com/f/nordic-q-a/52545/receive-external-data-through-uart-on-thingy-91 
https://devzone.nordicsemi.com/f/nordic-q-a/51355/inputs-via-gpio-on-the-thingy-91 

You can find more info in the hardware description of the Thingy91 and you can download the hardware files(Link to direct download) and including a pdf from our product page.

Regards,
Jonathan

[Adeel]

Hi Jonathan,

Thanks for the links. I referred to the hardware files and finalized the pins thereafter.

I have gone through the links you suggested me. I need modem tracing so I don't want to cut the solder bridges on MC_If[0-7]. That leaves me with only options of TP7 , TP32, TP33 for my uart. 

Could yo verify whether these could be used seemlessly.

Further, could you let me know how I can use P6 pins (originally or nr52840) for nr9160 ?

Regards,

Adeel.

[JONATHAN LL]

Hi,

P6 is connected to nrf52840, to get to those pins you can communicate between nrf52840 and nrf9160. Setting up a passthrough on the nrf52840 where you get the UART from sensor to nrf52840, and UART from nrf52840 to nrf9160. Look at the connectivity bridge example for guidance on how to set it up. 

 

Adeel said:

That leaves me with only options of TP7 , TP32, TP33 for my uart. 

 Those are the only access points to a nrf9160 GPIO. 


May i ask what sensor you are connecting since it is using UART and not i2c or spi?

Regards,
Jonathan

[Adeel]

Hi,

I am connecting a AST-3P device that works on Modbus protocol. So, I require a RS-485 communication through UART , using Tx, Rx, RTS, CTS. I can pin up RTS/CTS together to 1 pin so I was looking for 3 pins that I could use directly for Tx, Rx, RTS/CTS. 

To start off, I have configured this overlay file (thingy91_nrf9160ns) in my project.

&uart1 {
	current-speed = <9600>; 
	status = "okay";
	tx-pin = <13>;
	rx-pin = <16>;
	rts-pin = <10>;
};

I also changed the thingy91_nrf9160_common.dts file with the same pin configuration using uart_1.

Is this the only changes required to enable uart_1 in the thingy91 board ?

Regards,

Adeel.