I have an original Arduino UNO R3 that I bought and an Arduino Severino (S3V3) that I've built.
I have no problems uploading sketches to the UNO, but sometimes, when uploading to the Severino board, I have to hard reset it at a specific time during the upload process, when the IDE says something like this below:
avrdude: Version 5.11, compiled on Sep 2 2011 at 19:38:36 Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/ Copyright (c) 2007-2009 Joerg Wunsch System wide configuration file is "C:\arduino-1.0.3\hardware/tools/avr/etc/avrdude.conf" Using Port : \\.\COM1 Using Programmer : arduino Overriding Baud Rate : 115200 avrdude: Send: 0   avrdude: Send: 0   avrdude: Send: 0  
If I don't reset it when one of the
Send messages are being displayed, I get the
not in sync message, as below:
avrdude: Recv: avrdude: stk500_getsync(): not in sync: resp=0x00
Other times, if I'm lucky, I can upload to the Severino board without having to reset it.
So, my questions are:
Why does that happen? Why Severino needs a hard reset during upload?
Why is the problem intermitent? Why does it happen sometimes and others it doesn't?
How can I fix that problem? Is there a simple change to the Severino design that would fix that?