Connect to multiple Segger J-Link debuggers

[AmiguelS]

Hello!

I need to interact with two J-Link debuggers, connected to the same PC at the same time. I would then read and write data to the devices connected to the debuggers.

To send/receive the data, I was thinking of using telnet, and here is where the problem arises. Both debuggers would be connected to port 19021, making it impossible to select which device gets what data. Is there a way to change the port to which a debugger connects to?

I am also open to suggestions on different methods to read/write data through the J-Link probes. Data transfer would be handled and triggered by a python script, not by the user.

[AmiguelS]

Got it working! For the Telnet port to be visible, either JLinkExe or JLinkGDBServer have to be running. When starting JLinkExe there are two important command line options available - SelectEmuBySN and RTTTelnetport - allowing you to configure which Segger is mounted on which port.

Using these option I was able to configure each Segger to show up on a different port and then connect to both at the same time.

To manage the data on Python I used the standard telnetlib.

Edit: telnetlib dicards packets whose content is 0x00 or "\021", so I had to use an edited version of this library.

[Ole Bauck]

Hi,

Since you are already planning on using python I would try out pynrfjprog. You can connect to multiple devices and talk to them using RTT. See for example the rtt_open(), rtt_read(..) and rtt_write(..) functions.

Ole

[SRA]

FWIW, in case no one tells you guys what you do right.... Having python binding for nrfjprog is REALLY helpful for planning out how I'm going to set up a production programmer. I haven't used it yet, but so long as it works I'm very excited to use this option.

[Mathias]

How many boards did you try to telnet to at once? Because I'm trying with 9 boards but when I send a command over telnet to more then 3, not every board receives the command. And when I test each telnet connection seperately, they all receive the command when I send it.

[AmiguelS]

Hello. I have successfully established connections to 4 devices at once. However, sending and receiving information was never concurrent between any of them.