SIMtrace2 has a serial debug interface. It requires a serial-over-audio-jack cable that sysmocom sells in their webshop.
The serial output looks like this:
=============================================================================
SIMtrace2 firmware 0.8.1.66-e6e7, BOARD=simtrace, APP=trace
(C) 2010-2019 by Harald Welte, 2018-2019 by Kevin Redon
=============================================================================
-I- Chip ID: 0x28900960 (Ext 0x00000000)
-I- Serial Nr. 51203220-48483753-33303320-39313033
-I- Reset Cause: user reset (NRST pin detected low)
-I- USB init...
USBD_Init
SetAddr(19) -W- Sta 0x888A8 [0] -W- _ -W- Sta 0x888A8 [0] -W- _ -W- Sta 0x888A8 [0] -W- _ SetCfg(1) cfgChanged1 -I- calling configure of all .
-I- Sniffer config
-I- calling init of config 1...
-I- Sniffer Init
-I- entering main loop...
-I- USB is now configured
-W- Sta 0x88828 [0] -W- _ -E- USART PARITY Error
-E- USART PARITY Error
-I- ISO 7816-3 state 0->1
The way the simtrace authors seem to use:
git clone https://gitea.osmocom.org/sim-card/simtrace2.git
cd simtrace2/firmware/
make log
However, that somehow doesn't work for me. I'm constantly getting "Unknown command" messages:
Dec 14 15:08:04 Unknown commn k
Dec 14 15:08:04 Unknown comman n
Dec 14 15:08:04 Unknown comman n
Dec 14 15:08:04 Unknown comman U
Dec 14 15:08:04 Unknown comman m
Dec 14 15:08:04 Unknown comman o
Dec 14 15:08:04 Unknown commad''
Dec 14 15:08:04 Unknown commad''
Dec 14 15:08:04 Unknown commad''
Dec 14 15:08:04 Unknown commad''
Dec 14 15:08:04 Unknown commad''
Dec 14 15:08:04 Unknown commad''
Dec 14 15:08:04 Unknown commn m
Dec 14 15:08:04 Unknown comman w
Dec 14 15:08:04 Unknown comman
Dec 14 15:08:04
Dec 14 15:08:04 Unknown comman o
With minicom instead, there is no issue. Just remember to set the baudrate to 921600