[OpenOCD-user] RTT on the AM243x-Launchpad

[Jonathan P. <jon...@fe...>]

I’m using SEGGER’s RTT Protocol on the AM243x-Launchpad, and I’m seeing some issues. I can connect and load code just fine - I’m using these commands to start an RTT server, and that all works:

monitor rtt setup 0x70000000 0x10000
monitor rtt start
monitor rtt server start 19021 0

I can then connect to port 19021 and read out the RTT data – but only when I’m single stepping the code. If I let the code run, I see

Error: [am243.cpu.main0_r5.0] not halted
Error: [am243.cpu.main0_r5.0] not halted
Error: [am243.cpu.main0_r5.0] not halted
Error: rtt: Failed to read up-channel 0 description

The RTT socket then stops outputting anything. Running “rtt stop” and then “rtt start” fixes it, but again, only whilst single stepping. As soon as I let the CPU run then it breaks.

My OpenOCD was compiled from source, and is running on Apple Silicon macOS. It reports: Open On-Chip Debugger 0.12.0+dev-01931-g6834f022b (2025-04-07-10:40)

I’m running OpenOCD with: ./src/openocd -s tcl -f board/ti_am243_launchpad.cfg

The JTAG probe is naturally the on-board XDS110 – there doesn’t appear to be any way to use a different probe with this board.

Any insight gratefully received.

Jonathan

--
Jonathan Pallant
Senior Embedded Systems Engineer
t. +44 20 4571 3689
m. +49 151 2845 8745
Ferrous Systems UK Limited
201a Victoria St.
LONDON
SW1E 5NE