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Author Topic: Standalone Mega2560 boot time  (Read 4566 times)
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Did you put the pull-up resistors on them?
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Is this really necessary ? See the pictures, SNR > 200.


* 130131-Mega2560Rx.jpg (364.51 KB, 1453x1105 - viewed 16 times.)

* 130131-Mega2560RxFirst15ms.jpg (324.75 KB, 1449x1115 - viewed 17 times.)

* 130131-Mega2560Tx.jpg (383.89 KB, 1531x1183 - viewed 18 times.)
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We are running out of other options, that's why I suggest it.
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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?
« Last Edit: February 02, 2013, 10:49:12 am by PavelK » Logged

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PavelK, this exactly the same problem for me. I'm glad to know it's not a problem with my board  smiley !

On my board, if I reset the board while serial monitor is open, it starts immediately. You can try.
« Last Edit: February 03, 2013, 11:09:48 am by gabidanpremier » Logged

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See reply #30.
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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.
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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).
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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.
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I agree. I don't know of any "wait 10 seconds before doing anything" fuse.
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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?
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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).
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I tried your suggestion, but the 9.5 seconds delay is still there.
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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
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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.
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