OK, picked up the Mega2560 from my friend last night, and tested it out on the Lenovo Win7 32bit desktop and HP Win7 64bit laptop, and it works fine on both. The only variation from the Uno is the driver takes a long time to load (2-3 minutes - OK maybe not that long in the big scheme) and opening the serial monitor takes a while to reset the Mega - maybe 5 seconds. The Mega works well on our LED and LCD shield and takes only slightly longer to load.So the issue looks like a Dell issue. Maybe if anyone has a dead Mega2560, please report the make, model, operating system, and any other details which are show when you right click on My Computer and select Properties.
Hey All, I had a similar issue when I was trying to use an Uno as a boot loader, and I think the trick is that the chip is getting reset part way into the upload. The reasons this seems plausible are : A - someone mentioned it looked like his board had resetB - after a half-assed attempt at uploading, my board just starts up the old code (i.e. looks like it reset)C - It seems correlated to length of code, and I have no issue uploading the blink code, ever. Anywho, the hardware solution to this software problem is to toss a BFC (10uF or so, I used an electrolytic) between the Reset pin and ground. What this does is it stops the device from getting reset by little transients that I believe are associated with the serial printing stuff. Hope this works for Y'all, in the end I got it working with Arduino 023 and a 49K program.EDIT: This worked great briefly but now it has gone back to it's old ways of not working. -Shibbs
I've got this issue today after change my sketch to print three exclamation characters in sequence to the serial port:Code: [Select]Serial.println("!!!");I'm using Mega 256 with a Ethernet shield however this happens in any sketch, even Blink.ino.It looks like to me that this is a kind of reserved word for the compiler or for the firmware.Anyways I've just removed one exclamation character and it is working fine now.