Hi, I just unpacked my Mega2560 and got it working with Blinky. I looked at the PCB (R2) and could not see the crystal that is supposed to drive the cpu. There is a crystal at the 8U2 but only that one. How is the clock configured on the Mega2560?
It uses a ceramic resonator.
Mike, Look at this picture of the new revision and see if you can see the resonator or the second crystal.
I think I may have found it. It is a minute little thing that looks like a resistor to my old eyes. Under the lens it has six pins. Unfortunately the documentation on the website is not up to date so I could not reference from there.
That's it just above the 3v3 and 5v socket connections. There's a resistor just to the right of it.
Do you know if the latest schematic and layout are available somewhere? I normally use the Arduino to demonstrate the concept and then do the design for the hardware from there. I have not used the 2560 before and would like to make sure that my design at least looks like something that works already.
I think all the schematics are in the main Arduino site's hardware page, here's the mega2560 one
Rob, That is what I got. The layout does not match what I see on the board but if the schematic is correct, that is good enough for me. Thanks for the trouble man.
The layout does not match what I see on the board
It should but I wouldn't trust their documentation 100%, always apply a sanity test.