Go Down

Topic: Standalone Mega2560 boot time (Read 5039 times) previous topic - next topic

Nick Gammon

Did you put the pull-up resistors on them?
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

gabidanpremier

Is this really necessary ? See the pictures, SNR > 200.

Nick Gammon

We are running out of other options, that's why I suggest it.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

PavelK

#33
Feb 02, 2013, 03:38 pm Last Edit: Feb 02, 2013, 04:49 pm by PavelK Reason: 1
Hey I have the same exact issue with my mega2560. But mine is a genuine arduino I bought. It works perfectly but if I open serial monitor it take about 10 secs to start running again. BUT if I open the serial monitor I can press the reset on the mega and it will start right away?

gabidanpremier

#34
Feb 03, 2013, 04:40 pm Last Edit: Feb 03, 2013, 05:09 pm by gabidanpremier Reason: 1
PavelK, this exactly the same problem for me. I'm glad to know it's not a problem with my board  :) !

On my board, if I reset the board while serial monitor is open, it starts immediately. You can try.

Nick Gammon

Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

PavelK


See reply #30.


I don't understand why I need the phillip resistors one either Tx or Rx pins. I will try that. Also I'm kinda new to arduinos. How do I edit the fuses?

Btw my brother had a mega2560 and has same problem. It's not really a big problem just wondering why it does that.

Nick Gammon

Quote
How do I edit the fuses?


Cautiously. If you change the wrong things you may brick the processor. Make sure you understand what you are doing. Preferably key in your existing fuse values into a calculator, and then just change one bit.

http://www.engbedded.com/fusecalc

If you have an external programmer you can change them with avrdude (like an USBtinyISP programmer for example).
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

gabidanpremier

PavelK, if you've never changed the fuses settings on your Mega2560, I don't think there is a reason why you would do it now.

If you just want to solve the 10 sec issue, you wont solve anything by playing with the fuses settings.

Nick Gammon

I agree. I don't know of any "wait 10 seconds before doing anything" fuse.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

PavelK


PavelK, if you've never changed the fuses settings on your Mega2560, I don't think there is a reason why you would do it now.

If you just want to solve the 10 sec issue, you wont solve anything by playing with the fuses settings.


So what will solve the problem?

Nick Gammon

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).
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

gabidanpremier

I tried your suggestion, but the 9.5 seconds delay is still there.

retrolefty

I would put a digital volt meter on the reset pin (and ground) and see what voltage you read there during this 9.5 second nothing happening time.

Lefty

Nick Gammon

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.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

Go Up