JTAG port help

For Developers
1

I have a router with the following JTAG connector:

87a0a11c394fd7531fbc48365c7203434186fc63
87a0a11c394fd7531fbc48365c7203434186fc63386×651 93.6 KB

that according to the following schema is mapped in the following way:
Schermata del 2022-02-14 13-36-55

I created an unbuffered parallel port according to the following schema:
jtagunbufferedrouter

The problem is that urjtag tells me ,after issuing the detect command:

TDO seems to be stuck at 1

Do you think it is a problem related to the missing resistors on the board?
I measured using the multimeter the voltage between GND and other pins and found the following interesting voltages:

  • pins 2, 4, 6, 8, 10 are ground on the router.
  • on TDI pin 3 there is a 2.2V value
  • on TDO pin 5 there is a 0V value
  • on TMS pin 7 there is a 2.2V value
  • on TCK pin 9 there is a 0V value
  • on pin 14 the voltage is 0V
  • pins 1 and 11 (nTRST and nSRST) are at 0V
2

Have you tried different software? That message appears in some other OpenWrt trhreads where it was addressed that way if I read correctly.