Duemilanove Board - Whats the component?

Forum 2005-2010 (read only) General Frequently-Asked Questions
#1

I have printed a few PCB’s of the Duemilanove (with local modifications :() ) now there is this marking 100_NM on the original duemilanove .brd file to the left of the crystal. What component is this? I’ve been breaking my head to figure it out. Also what would be the role of the fuse? will it be really dangerous to skip the fuse? Can it really affect the computer through usb?

Cheers,
Prakash

#2

Can it really affect the computer through usb?

Yes you can blow up the USB socket if you put a short on it.

Any chance of a photo of where that component is? Try tracing where it goes to.

#3

Most PCs have their own USB fuse, but apparently not all of them. In the latter case, you can crash your computer or even permanently damage the MB by accidentally shorting things on the Arduino side.

If you’re talking about R2 with the value 100_NM, I believe this was an alternate attempt at implementing auto-reset, and the NM means “Not Mounted”; it this component does not actually exist on production Arduino boards…

#4

Yes its R2… wow! NM => Not Mounted… lol and i’ve been breaking my head with all possible resistance values… so is it ok to skip it? or should i use a jumper or something?

It goes from RTS pin on FT232RL to a junction connecting the resets on the power supply and the atmega…

http://www.4shared.com/file/118636843/7b3ff9bd/arduino-duemilanove-schematic.html

#5

You should omit it entirely. It’s also left off of the real duemilanove boards…

#6

Thanks West. :slight_smile: I appreciate it.

#7

Do we ommit the entire trace or just the resistor but still connect Reset to RTS?

#8