Independent power?

14 Mar 2010

Hello again,

I know mbed is a prototyping microcontroller (but I'm too cheap to buy another :P), but would it be possible to power the LPC1768 with a battery? I.E the battery goes to a USB out, and that USB out goes into the USB in on the mbed, hence powering it.

Would this be possible? And what voltage and ampage can the mbed take (if anyone knows)?

Thanks,

Dom.

14 Mar 2010 . Edited: 14 Mar 2010

Hey Dom,

If you notice on the pin card you got with your mbed pin 2 (VIN) can take from 4.5 v to 9.0 v of power. If you just connect the + of the battery to pin 2 (VIN) and the - to pin 1(GND) your mbed will be powered and wireless :)


14 Mar 2010

Ohh, cool! Will try that when my breadboard comes.

 

Once again, thanks, Vlad!

20 Mar 2010

If i did, by accident, reverse the polarity of the battery holder, that would effectively murder the mbed, right?

20 Mar 2010

And how do I know the polarity of my battery holder? I know it's a stupid question, but i don't want to kill something that would cost me £45 to replace. It's a 3x battery holder. I'm guessing it's just that the pins are the polarity of the side of the battery they are nearest too, right? Or is it the other way round?

20 Mar 2010

Dom Johnson wrote:

If i did, by accident, reverse the polarity of the battery holder, that would effectively murder the mbed, right?

I do not think anything would happen, your mbed would just not run, but dont quote me on that one because I have never tried.

An easy was to check for polarity is using a multimeter. Place one wire on the red and one on the black, and if you get a positive voltage then the one connected to your red is positive, if its a negative voltage then the wire on the red is negative.

If you do not have a multimeter just connect the battery pack to an led and see which one is + and -, if you include a picture of your battery holder I could probably tell you which one is which.

Worst resort is just to follow the logic of the battery holder, track the + charge thought the batteries and see which wire it is connected to.

20 Mar 2010

A current limiting resistor will be needed for the LED!

20 Mar 2010

Leon Heller wrote:

A current limiting resistor will be needed for the LED!

Yes make sure you don't blow the LED