common flash hw write enable methods

Andrew Kohlsmith akohlsmith-linuxbios at benshaw.com
Sun Dec 1 21:58:01 CET 2002


So I've got linuxbios booting inside Bochs and I feel I'm confident enough to 
roll the dice and burn it to a real board (TSSOP package, no sockets) using 
/dev/bios.  

After some head-scratching, I realize that the hardware RP# and VPP are tied 
together, and at a logic low, preventing any flash attempts.  These are pins 
10 and 11 on the TSSOP part.  :-(

Now I imagine that these are tied to a MOSFET to +12V which is run off of a 
GPIO pin.  The question is, without tracing an 8-layer board out to try and 
identify how exactly reflash is enabled, how to reflash this?

I can always cut the traces and hard-wire to +12V but I'd like to see if I 
can't do this programmatically.  I have a number of boards I want to use and 
hardware hacking is something I'd like to avoid doing if possible.

Now I know that every motherboard is different and that there may be other 
things locking me out, but generally speaking is there an "industry standard" 
way of enabling/disabling BIOS reflash?  It's currently a PhoenixBIOS, so I 
imagine if I located a reflash tool and ran it in a Bochs session with a lot 
of I/O debugging I could figure out what it's doing but before I embark on 
that I'd like to see if anyone has any hints that may save me a lot of time.

Regards,
Andrew



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