An Altera CPLD "JTAG Unlocker"

Hi There,

From time to time I see people having Altera CPLDs on the "JTAG Lockout" st atus. I have a few EPM7128s on this state myself.

I wonder how difficult would it be to create an "eraser/unlocker". I know t his process can be done by the Master Programmers, but they are clumsy, com plex, impossible to find on eBay, incompatible with Windows 7/8 and/or USB, and VERY VERY expensive. What I am thinking about would be something simpler, which would imitate th e signals sent by the Master Programmer to erase the chip (thus freeing the JTAG pins for reprogramming). From that moment on, JTAG would be used to do the programming.

Have anyone ever seen something like this? Tried something like this? Succe eded? Have anyone ever seen the algorithm used by the master programmers? THere has to be some information out there, as programmers from other vendo rs than Altera are able to unlock the chips.

This is definitely something that would sell out on eBay I guess. I see the (magic) GQ-4X USB programmer does program Alteras (still using JT AG, though), and it has an adapters for the CPLDs (ADP-095, ADP-096 and ADP

-097). If its driver could be modified to send such signals, then we alread y have the hardware, no need to build one.

Yes? No? Anyone?

Cheers, Marcelo.

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