The GPIOs on the 40-pin header are provided by RP1 - they have no JTAG access to the SoC (or anything else). Debugging must be via the 3-pin JST header. You can either use a dedicated SWD debug interface such as the Raspberry Pi Debug Probe (which gets you a serial cable as well), or use a JTAG cable with this wiring:(*) Connect the yellow/TDI wire via an inline 470Ohm resistor.
The colours are those found on an FTDI C232HM - for other devices you'll have to use the signal names.
I've used both the FTDI and the Debug Probe successfully.
Code:
| Wire | Name | Pin | | ---- | ---- | --- | | Orange | TCK | 1 | // UART TX | Black | GND | 2 | | Green | TDO | 3 | // UART RX | Yellow | TDI | 3* |The colours are those found on an FTDI C232HM - for other devices you'll have to use the signal names.
I've used both the FTDI and the Debug Probe successfully.
Statistics: Posted by PhilE — Thu Jul 03, 2025 8:52 am