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Author Topic: Lilypad: switching off USB power to the board?  (Read 820 times)
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Hi all,
Can anyone tell me how I can switch off USB power to the Lilypad and have it run from external power only, while still being connected to the computer?

I'm using the FTDI 6-pin Basic breakout board with the Lilypad 328.
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I can see no valid reason for this.
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Hi kitty, let me elaborate...

As I understand it, Arduino Duemilanove and likely other boards have a small jumper that you can use to select whether to power the arduino through USB power or through an external power supply (despite it being connected to the computer).  My question is whether this feature is also on the Lilypad and/or FTDI breakout board.

I'm running some battery life tests that involve using a Lilypad, a Lilypad sensor, and various battery combinations to determine the running time of the Lilypad components with said combinations.  I'm running a program in Processing that is essentially a timer from the first serial event until the Lilypad no longer transmits serial data (when the battery runs out).  This is why I am not interested to have USB powering the setup.

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According to the schematic, the Lilypad appears to have the USB power in parallel with the external voltage input.
You can not switch between them without doing one of three things:
A. Modify the board
B. Chop up a USB cable to use an external voltage source
C. Find a new way to implement the check for out of power
Also, do not connect an external power source to the board while it is plugged into the USB port or it may damage your computer or your power source or both due to voltage differential.

Schematic is here in case you want to view it: http://www.arduino.cc/en/Main/ArduinoBoardLilyPad Very confusing.
« Last Edit: January 09, 2011, 02:06:44 am by smeezekitty » Logged

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Pretty much answers my question, thanks!
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