12:01 <frankplow> Hi, I am trying to use OpenOCD to read a SWV trace from a J-Link probe. When I try to initialise the trace, it causes a fatal error in the emulator as determined by the probe's indicator LED. OpenOCD does not report any error messages however there is no SWV output. J-Link's SWOViewer software works fine.

12:03 <frankplow> The target device is an nRF52832. Here is how I am trying to initialise the SWV trace:

12:03 <frankplow> tpiu create nrf52.cpu.tpiu -dap nrf52.dap -ap-num 0x0

12:03 <frankplow> nrf52.cpu.tpiu configure -protocol uart -traceclk 64000000 -output itm.fifo -formatter off

12:03 <frankplow> I have tried both a 64MHz and 32MHz traceclk and explicit and automatic pin-freq but with no luck.

12:03 <frankplow> nrf52.cpu.tpiu enable

15:35 <Haohmaru> is that 64MHz uart bitrate? o_O

16:52 <frankplow> No, the traceclk is the frequency of the TPIU peripheral. It's usually just the core clock but I think for this particular MCU it's divided (the datasheet calls the divisor TRACEPORTSPEED). OpenOCD calls the SWO/UART frequency pin-freq and it is much lower, ~1MHz, but the protocol should be able to negotiate this I think. I've tried explicitly setting pin-freq to 1MHz and some other values but to no avail.