I found this presentation really interesting, in no small part because I've been doing a lot of reading on JTAG for work lately.
One idea I'd like to add: using EXTEST to identify the pins. If I understand the command correctly, it seems as if one could utilize the BSDL file to generate a series of EXTEST patterns that would each set one I/O pin high and the rest of them low. Then, you could just probe the IC pins until you found the high one. This is more or less the reverse of what he describes- he's applying a voltage and using the SAMPLE command to detect it.
To my understanding, this EXTEST method could also be used instead of the suggestion on slide 90 to write some VHDL/Verilog to copy a known input to an unknown output.
Doing any of this in an automated/programmatic way would probably take a better software suite than 20-day one mentioned, or at least a lower-level tool of some sort, I suppose.
Setting pin high or low can get you in conflict with other devices connected to that pin. In the best case you wouldn't tell which pin is which and in the worst you could damage that other device.
Nice presentation. Around slide #84 or so, for a good time don't just put in a current limiting resistor, put in a current limiting resistor and a LED. Hmm the LED lit up I guess the pin is a grounded pin?
[+] [-] anoonmoose|10 years ago|reply
One idea I'd like to add: using EXTEST to identify the pins. If I understand the command correctly, it seems as if one could utilize the BSDL file to generate a series of EXTEST patterns that would each set one I/O pin high and the rest of them low. Then, you could just probe the IC pins until you found the high one. This is more or less the reverse of what he describes- he's applying a voltage and using the SAMPLE command to detect it.
To my understanding, this EXTEST method could also be used instead of the suggestion on slide 90 to write some VHDL/Verilog to copy a known input to an unknown output.
Doing any of this in an automated/programmatic way would probably take a better software suite than 20-day one mentioned, or at least a lower-level tool of some sort, I suppose.
[+] [-] omgtehlion|10 years ago|reply
[+] [-] xwintermutex|10 years ago|reply
[1]: http://hackaday.com/2013/10/02/jtagulator-finds-debug-interf...
[+] [-] teh_klev|10 years ago|reply
https://docs.google.com/presentation/d/13p6O0C3aY-LSeqGAjfEg...
[+] [-] amckenna|10 years ago|reply
[+] [-] VLM|10 years ago|reply
[+] [-] jakeogh|10 years ago|reply