HELP! S4 suddenly stopped emulating
Posted: 14 Nov 2011 12:34
I have a weird problem. I have been running two S4's emulating two 27C4001 eproms on the same circuit board. Suddenly, one of the emulations won't work no matter what I do. While attempting to isolate the problem, I determined that either S4 will successfully emulate one of the chips, but not the other. I have done all of the cable swapping, etc. I can think of.
Since I have two S4's and two cables, and any combination of these will successfully emulate one of the chips, I think I can safely say that this is not an S4 or a cable problem.
When the eprom itself is present in the actual device (not the S4), the device works fine, but the device simply will not operate when the eprom is emulated by the S4. Previously, this setup worked fine with both chips being emulated, but now I am completely stuck.
I am sure that the data being read from the eprom into the S4 is correct. I've compared it with a previously saved version from when everything was working.
Again, this setup had previously worked, so something has mysteriously changed to cause this problem.
What sorts of factors can interfere with emulation? Have I somehow crossed some electrical noise threshold? Should I try a shorter cable? Any advice appreciated!
Since I have two S4's and two cables, and any combination of these will successfully emulate one of the chips, I think I can safely say that this is not an S4 or a cable problem.
When the eprom itself is present in the actual device (not the S4), the device works fine, but the device simply will not operate when the eprom is emulated by the S4. Previously, this setup worked fine with both chips being emulated, but now I am completely stuck.
I am sure that the data being read from the eprom into the S4 is correct. I've compared it with a previously saved version from when everything was working.
Again, this setup had previously worked, so something has mysteriously changed to cause this problem.
What sorts of factors can interfere with emulation? Have I somehow crossed some electrical noise threshold? Should I try a shorter cable? Any advice appreciated!