On Sat, 15 Nov 2008 18:50:23 -0500, "Tom Sylla" tsylla@gmail.com wrote:
You will have a "target" PC for which you are developing firmware. Some sort of PCB or protoboard with one PLCC socket and one PLCC stacking connector will be plugged into the ROM socket of that PC. A ROM device will be plugged in to the PLCC socket of your PCB. Another PC will be a development system, and a USB and parallel cable will connect from your PCB to the development PC. With the target PC *off*, you will re-flash the ROM from the development PC
Yes, you got it.
If that is an accurate description, I think you have a few more things to be careful about. The hazard you are asking about deals with the 3V from the target PC turning on and fighting the ~3-5 of your protoboard. What about while you are "flashing"? You will be injecting 3V from your prototype into the 3V rail of the target motherboard, which is not generally a good idea.
True, good point.
Also, you will be attempting to drive the LPC signals against a "dead" motherboard, which may or may not work.
If the ROM is socketed, why not just program the ROM in your device, then pull it out and put it in the target? If you really want the convenience of not having to do that, you'll probably have to be a little more careful about not fighting the target.
Ah one of the functions, will be the ability to flashed soldered on bios's.
I'm thinking for now to keep the LPCflasher basic and cheap, just using the schematic without the diode for now. We could always come up with power fault modifications and add those to daughter cards. They don't necessarily need to be on the LPCflasher main board.