Go Down

Topic: Standalone Mega2560 boot time (Read 4 times) previous topic - next topic

retrolefty


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.


Your correct again as usual. This thread has been going so long I forgot I even posted on it before.  ;)
I've got to admit this is one of the more unsual and puzzeling symptom problems that I can recall here.

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.

Lefty

Riva

The final thing I can think to ask is what bootloader do you have on the chip? Older bootloaders used to wait about 8 seconds from reset for possible reprogram commands before launching the main code. I don't have a mega so I'm not sure if it ever had this old style bootloader but when your clutching at straws...

cyclegadget

Quote
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.



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.

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!

retrolefty


Quote
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.



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!

gabidanpremier

Riva, the bootloader used is detailed in my original post and in the reply #16. This last one is the one I'm using at this moment. Overall, I tried something like 3 or 4 different ones to try to solve this problem.

cyclegadget


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).



I made a new board.txt and called it "mega special fuse" and made the low fuse 0xC6 as you suggested. Then I burned the new bootloader fuses to my Mega board.

It seems to have helped my upload issue. I still need to do more testing to be sure. I can say for sure that it has worked nicely so far!

Go Up