Shell over UART between nrf52840DK and nrf9160DK not working(SDK v2.6.1)

[harry4951]

Hi,

I need to setup shell interface on both sides to exchange sensor data via uart.

 

The connection is as follow:
cable 1: nRF52840DK Pin (TX - P1.02) → nRF9160DK Pin (RX - P0.21)
cable 2: nRF52840DK Pin (RX - P1.01) → nRF9160DK Pin (TX - P0.22)
cable 3: nRF52840DK GND → nRF9160DK GND

Now the issue is

if both cable 1 and 2 are connected, no output from either side.

if only cable1 plugout, nrf52840 can output the data received from nrf9160.

if only cable2 plugout, nrf9160 can output the data received from nrf52840.

I attach the code, can you please test and see how can we fix it?

Note that I have to use the shell interface, because in our custom hardware the DFU(smp, mcumgr) is needed sharing the same uart. After testing, seems that so far only the shell and DFU can coexist. 

Thanks in advance!

/CJ

PS: strange formatting after posting, lots of line spacing is discarded.

4604.test_bi_shell.zip

[Hakon]

if both cable 1 and 2 are connected, no output from either side.

I'm testing this now, and I get data occasionally when both cables are connected. I still don't know the reason but I will do some more debugging.

[harry4951]

Thanks for the investigating, any progess?

[Hakon]

Checked a few things, but I'm still not sure why this happens. Have you tried enabling flow control on the shell uart?

[harry4951]

I cant use the flow control, since this setup will be applied to our custom PCB, which only has TX and RX lines.

[Hakon]

It looks like the shell commands received are somehow altered, this is when both cables are connected;

This with one cable disconnected;

You can see that in the first case there are some characters inserted that makes the command different and thus not triggering the callback. I guess when the nRF9160 is sending as well as receiving, somehow this buffer is overwritten.

[Hakon]

I made one for observation. It seems like the command is being written to the wrong position in the command buffer. I still don't know why it happens.

[harry4951]

Hmmm strange, do you think it is a bug in the library?

[Hakon]

It could be. It seems like it is inserting characters in the wrong positions in the buffer all the time. The shell library is a big mess so it's hard to understand where it goes wrong.