Arduino Uno - problem with external power supply

Forum 2005-2010 (read only) Software Troubleshooting
1

Greetings,

I have an Arduino Uno (and code) which functions perfectly when powered via USB from my computer.

However, when I try to power it via an external power source only, it only executes once with a reset. Every time I press the reset button, it runs once, but never continuously.

Here are the power supplies I have tried:

  • 12 VDC 800 mA connected to arduino power jack
  • 12 VDC 1 A connected to arduino power jack
  • 5 VDC 500 mA ipod charger connected to arduino USB port

Is there a jumper I need to configure, or some sort of manual configuration (e.g. resistor) needed somewhere?

Let me know what you think.

P.S. - here is what my arduino is running:

  • chronodot clock
  • two SHT11 temperature/humidity sensors
  • one LM35 temperature sensor
  • one photoresistor
  • one ethernet shield :cry:
2

it only executes once with a reset.

It only executes what once? How do you know that it only does something once?

3

A guess, maybe the Uno is waiting for data that never arrives, because one of the other components is not powered correctly. Maybe put some debug statements in to find where the software is at.

4

Guys,

thank you for your responses.

UPDATE - I thought I fixed this by removing the serial.begin and serial.print statements.

It worked sporadically, but does not appear to be fixed.

I now believe the problem is related to the ethernet shield.

Here is a thread about it.
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1282325583