UART communication between two boards

[DeveloperZ]

Hi,

I am trying to establish UART communication between two nRF52 Dev boards. I flashed both of them with UART peripheral example from 15.2.0 SDK and connected TX,RX and GND pins.

Here, I encountered a weird issue where the two way communication(two terminals are recording the data when I enter data on any one terminal) is taking place with only one connection (TX from one board to RX on another / Connecting RX of both connectors) and nothing is being displayed on terminals when TX on both boards are connected. Can anyone explain this?

Thank you.

[Joakim Jakobsen]

Hi.

I'm not sure if I understand exactly what your setup looks like.

You have only connected TX from one board to RX on another board, and are able to acheive two way communication? You also get two way communication connecting only RX from one board to RX on the other board?

If you have two DK's (Board A and Board B),
You should connect TX from board A to RX on board B and TX from board B to RX on board A.

Could you provide some more information as well?
Which SDK are you working with? nRF52 DK? Custom board? etc. 

Best regards,
Joakim

[DeveloperZ]

Hi,

Joakim Jakobsen said:

You have only connected TX from one board to RX on another board, and are able to acheive two way communication? You also get two way communication connecting only RX from one board to RX on the other board?

Yes, this is what I was facing. I was on vacation and just returned today. So, didn't have much time working on this.

Joakim Jakobsen said:

If you have two DK's (Board A and Board B),
You should connect TX from board A to RX on board B and TX from board B to RX on board A.

This is what I have started with. Few weeks ago, it was working perfect with these connections but later it started to behave weirdly where the two way communication was occurring with only one connection. 

I am working with 15.2.0 SDK, examples-> peripheral->uart. I didn't create any custom board. I am using pca10040.h file only. And yes, I am using nRF52 DK's with nRF52832.

Thank you.

[DeveloperZ]

I tried it again today and the result was the same!! One connection (TX on Board1 to RX on Board2 / TX on Board2 to RX on Board1 / RX on both boards) is resulting in a two way communication!!

[Joakim Jakobsen]

Hi.

Thanks for the response.

I haven't been able to reproduce this yet.
Have you made any changes at all to the example, i.e changed the TX/RX pins?

Regards,
Joakim

[DeveloperZ]

Hi,

I downloaded the stock SDK and and used the UART peripheral example directly. I haven't made any changes to the example.

Thank you.

[Nguyen Hoan Hoang]

make sure you disabled flow control.