Reply #21 appears to indicate that reset goes low only briefly.However apart from the presence of the capacitor which is charged when RTS goes low, I can't see any reason why the two different reset methods should behave differently.
Almost remind me of the rare but repeatable DTR auto-reset 'lock-up problem' that that led to arduino adding the reverse biased diode from reset pin to Vcc on Rev3 boards, which 'fixed' that problem.
QuoteAlmost remind me of the rare but repeatable DTR auto-reset 'lock-up problem' that that led to arduino adding the reverse biased diode from reset pin to Vcc on Rev3 boards, which 'fixed' that problem. I have a Mega that looks like an real Arduino but, I suspect it is a clone. I have serial upload problems that do seem to be related to the DTR "lock-up" and sometimes when the upload is working, it freezes before the upload is complete.Well the symptom of the DTR 'lock-up' if a recall accurately, is that the upload would complete but the sketch wouldn't start, unless you then pressed the manual reset switch that would then start the sketch running. Failing to complete the upload on a mega board sounds more like the problem if you have 3 ! characters (!!!) in a row anywhere in your sketch code the bootloader would stop processing characters and instead jump to a 'monitor mode' waiting for user monitor commands which are not going to be coming from the IDE. This latter problem is strictly a bootloader bug/feature problem that only upgrading to a 'fixed' mega bootloader will solve.Lefty I will try out the diode idea and the fuse change to see if it works. Currently, my board is almost unusable as I can rarely get a successful upload!
I got an idea from another thread, where the serial port was interfering with the clock.Try changing the low fuse to indicate a "full swing oscillator with fast rising power" (low fuse: 0xC6).