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1  Using Arduino / Displays / Re: Problem with 16x2 display on: January 10, 2013, 12:47:36 pm
I'm guessing you see 5v on Vin but something else on Vcc.

Yes, that's right.
Then I'll look for another power supply. Thank you very much for your insights, appreciate it!
2  Using Arduino / Displays / Re: Problem with 16x2 display on: January 10, 2013, 11:36:53 am
Sorry for not mentioning it, I've got the Uno. Thanks for the tip with the Vin - when I plug the display in the Vin it works (makes sense smiley)
Is this ok for prolonged usage, or should I switch to a 7-12V power supply?
3  Using Arduino / Displays / Re: Problem with 16x2 display on: January 10, 2013, 10:54:29 am
No, I got it from a German store.
4  Using Arduino / Displays / Re: Problem with 16x2 display on: January 10, 2013, 10:41:04 am
This is the ebay auction I got the display from: http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=251049844026 As you can see it looks different in the item description - that's China for you I guess  smiley
Unfortunately it didn't come with a data sheet...

I reworked the code, included a delay of 0.5 s, but no change - but the problem is something else entirely as I just found out:
It's the power supply. I bought a 5V/1A power supply, which I used when I took the photo. Just now I connected the arduino to my computer to upload a sketch - and now it works perfectly!

I checked the voltage on the 5V Terminal of the arduino: When I use the external power supply I only get 3. something Volts there, which explains why the contrast of the display was so low. But the power supply does output 5V when nothing is connected, and when I power the display separately with the power supply it works as well (but then I don't have a common ground, plus I don't want to use two power supplies).
How can this be, the external power supply has more juice than a usb port, right? Is this a problem with my arduino?

Edit: Nevermind, should've read the data sheet of the Arduino more carefully: 7-12V for the power supply , but 5V operating voltage  smiley-zipper
5  Using Arduino / Displays / Problem with 16x2 display on: January 10, 2013, 02:59:45 am
Hi!
I have a small problem with my 16x2 lcd display (HD44870 compatible). I connected it to my Arduino like described here: http://www.instructables.com/id/Hookup-a-16-pin-HD44780-LCD-to-an-Arduino-in-6-sec/
And it works, except for the fact that the characters are barely visible. V0 is connected to a 10k trimmer, when even when this is set to 0V the contrast is really low. If I reset the arduino and/or reconnect the display I sometimes get random charactes with decent contrast.
Any ideas?
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