ESP32-S3 "pad JTAG" port without burning efuses?

[projectgus]

Hi all,

Is there a way to enable discrete "pad JTAG" access, without burning any efuses on the chip?

There's a sentence in the reference manual that says "The CPU JTAG signals can be routed [...] using eFuses and when the user program has started, software control as well":

Screenshot_20250813_112510.png (98.59 KiB) Viewed 108 times

However, I can't find any memory mapped addresses for these ctrl_sel registers: maybe it's only the "USB_JTAG_BRIDGE_EN" function that's available to software control?

(Use case is: trying to JTAG debug an issue with USB support in MicroPython, so we need the USB port to be muxed to native USB. Don't want to sacrifice a board by burning efuses, if we can help it.)

[Sprite]

Hm, good point: it looks like you can re-route USB-serial-JTAG to GPIOs in software, but routing CPU JTAG to pads can only happen by blowing eFuses.