J5 on rpi2, vpu jtag, 8 pins
J5 on rpi4b, vpu jtag, 0.5mm pitch 8 pins

            use this one
1   TCK     8
2   GND     7
3   TMS     6
4   TDO     5
5   GND     4
6   TDI     3
7   TRST_N  2
8   RUN     1


> I think I have had one SD card corruption due to power pulling, but MANY SD card corruptions from using the JTAG debugger on the Videocore and forgetting to shutdown correctly. This is because the JTAG stops all the cores, even during SD card writes.

https://www.raspberrypi.org/forums/viewtopic.php?p=1750304#p1750304


https://www.raspberrypi.org/forums/viewtopic.php?p=1808846#p1808846
> I don't know why people think this is difficult to work with. Seems to work fine to me, but then I am using the recommend setup - Pi4, OpenOCD, Pico. Sometimes use VSCode, sometimes the command line. It all just works. Compared with dev systems I have used in the past, it's a joy! The only embedded system that I've used that is better is the one for the VideoCore, which is very good, but costs a lot.