| ??? 08/10/07 18:34 Read: times |
#143059 - You have stories, but no specifics Responding to: ???'s previous message |
Jan Waclawek said: it matters very much "in which way" the failure occurred!
I had a circuit with RC reset, which in multiple field installations failed - no matter in which way, but in my case it was almost always battery RAM content corruption, except the runaway coin hopper case - and which in the SAME installations (the same place, same mains installation, same people doing the same operations), just with adding a small board replacing the RC reset by a proper reset IC - starts to work without ANY problems (and believe me, those problems get reported regularly) - pray, explain, what mechanism other than the presence of proper RESET could possibly remedy the problems experienced before? Did anyone examine the operating circuit? Did you ensure that the minimal rise time of Vcc was met? Did you ensure that the Vcc-Gnd noise was under, say, 20 mV? I submit that this particular case was not sufficiently studied, and, in fact, not studied at all. Everything you've described is based on anecdotal observations, probably made over the telephone and no symptoms were studied with instruments by means of which you could establish that there were no other failure sources in the same instance. This happened with at least 4 completely different platforms (the 4-bitter in the hopper, 65C02 - I did not mention that story yet, classical 8031 and AT89C2051). I also have a 65C02 story related to reset. That one continued to exhibit odd behaviors despite the fact that 5000 boards were replaced with a circuit that was designed (not by me) with both DS1232 and DS1231 IC's. There was still occasional BBRAM corruption. I was asked to look into the problem, and, ultimately, reduced the on-board capacitance and inserted a DC power switch between the DC supply and the circuit board. No further problems were reported. I know this is a symptomatic description, so you might see it as not scientific enough, but for me, it provides the evidence firmly enough. Actually, there's no evidence of anything other than the incidental observation that there's some sort of problem. JW
From what I've read so far, from you and from others, nobody has ever studied this problem class at all. They have some problem and report it as a "RESET" problem because they've heard that there are RESET issues with the 805x. They then add the supervisor IC and hope for the best. It often works out favorably, so they keep their jobs. Nobody really knows what problem was encountered or whether it was solved. RE |
