Sending data to NRF52 over PCA10040/SWO

[John Waters]

Hello,

I have the following setup:

• a computer connected to a PCA10040 over USB
• a PCA10040 connected to a NRF52832 over SWO (SWD IO, SWD CLK, SWO, RESET).

I would like to send data from the computer to the NRF52832 using this setup (ie. nothing over BLE).

What is the best solution? I am a bit confused between JTag, JLink, RTT, SWO... If needed the PCA10040 can be replaced with something else but I cannot change the four pins on the NRF52832 side.

Thank you for your guidance,

[JONATHAN LL]

Hi,

You have a custom board and the only pins you have access to is (if it is a QFN packager) pin 21, pin 24, pin 25 and pin 26 ?



Then you can use serial communication like UART on pin 21 and 24, they are general purpose IO.

Regards,
Jonathan

[John Waters]

Thank you very much for your answer.

It seems the information I gave above is incorrect.

The pins we use are VDD [A7], SWDIO [G1], SWDCLK [F1] and ground (on BGA), and they're connected to the PCA10040.

Is something doable with this setup only? (since flashing and getting RTT logs is possible, I assumed sending data also was, and it seems JLinkRTTViewer can send data). That would be very convenient for our product.

If not, to be sure, are you suggesting we should add pins 21/H2 and 24/H1 to have a UART connection?

[John Waters]

Thank you so much. I can indeed send and receive data using the functions in SEGGER_RTT.h.

Last question. I would like to send data automatically. Is there a way to do it using Command Line only?

[JONATHAN LL]

Hi John,

I don't have a proper answer here for the last question, my best bet would be to have a script running that uses the terminal to do the things you want.  

Regards,
Jonathan

[John Waters]

What I can do is start JLinkExe, and in parallel use netcat on localhost 19021.

$ JLinkExe ... &

$ echo "cmd1\ncmd2" | netcat localhost 19021

I wish I could do both with one program. Something like:

echo "cmd1\ncmd2" | rtt_sender

[JONATHAN LL]

Hi, I have not tested this but i belive it should be possible. You will have to start a rtt-session regardless so i believe something along the lines of : start a JLink instance then echo in to localhoste. 

Good luck!

[John Waters]

What I mentioned works (JLinkExe + netcat).

If someone has a better idea in one command, I'll take it.

Anyway, thank you very much for your help Jonathan.