Humm… so, this could be a timing issue? When it appeared that JTAG was connected, actually the Halt command didn’t return anything, so I was wrong to write that Halt was working.
Today OpenOCD hasn’t ever successfully connected to the mt7620 via JTAG … this is the current screen capture -
ken@Ubuntu-coder:~/Downloads$ openocd -f tigard-jtag.cfg -f mt7620n.cfg
Open On-Chip Debugger 0.10.0
Licensed under GNU GPL v2
For bug reports, read
adapter speed: 2000 kHz
Info : clock speed 2000 kHz
Error: JTAG scan chain interrogation failed: all ones
Error: Check JTAG interface, timings, target power, etc.
Error: Trying to use configured scan chain anyway…
Error: mt7620.cpu: IR capture error; saw 0x1f not 0x01
Warn : Bypassing JTAG setup events due to errors
Tried lots of powercycles and everything else I could think of … with no changes.
I hooked up the router UART pins to the Tigard and watched the boot of OpenWRT in another terminal with Screen - that all looks normal to me.
For Tigard to successfully connect, do I need to time when I power-up Tigard or launch OpenOCD? I got the feeling from your JTAG lab 3 walkthough that those steps don’t matter, as long as the router has booted.
Anything else for me to try? Seems like a hardware issue to me. How could the JTAG pins be shorted? Could that happen if Tigard’s JTAG switch was once in the wrong position?