NG startup issue

Forum 2005-2010 (read only) Hardware Troubleshooting
1

Hi all, i'm running an NG and am having an issue with the kickoff:

when i have the jumper set to USB, and am bringing 9vdc 100ma into the external jack to run through an h-bridge, all is well in uploading, starting and running the sketch.

However, when i set the jumper to external, the power led lights up and the DE says uploading is fine, but the program never begins. No amount of reset-buttoning or waiting makes things better. IF, however, the jumper is set to external and the USB is still connected, the program will begin and will continue even if i remove the USB cable after startup, leaving me with the condition of having to have the computer connected to start things up.

Any ideas?

my new Duemilanoves should be arriving soon...

2

Sounds like the old floating serial pin problem.

http://arduino.cc/en/Guide/Troubleshooting#toc1

3

ah, that certainly seems likely. thanks for the link.

4

Thanks again, that solved it.

Just got my Duemilanove, and just wanted to be certain of one thing: the duemilanove doesn't have the dedicated 9vdc output that my NG has, only the 3.3 and 5? it's back to the 7809 for me?

5

If you are using a 9v supply you can get it from Vin. That is the same pin that was on the NG. But again, It's only 9v if your supply is. The only regulator on the board is 5v, the 3.3 comes from the FTDI chip.

6

so the 9v pin on the NG is unregulated? i had assumed it was regulated, because my unregulated 9v power supply runs about 11.5, and the '9V' pin outputs about 9.3.

7

Yep, it is unregulated. I am not sure why 9v was printed on the board other than use of a 9v supply was assumed? I'm guessing your supply was lower than you measured either due to the load or the diode, or possibly both.