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[on:]

hello, i just got a nokia 5110 display. since the display runs on 3.3 v it is recommended by some websites to use resistors or level shifters to limit the current. however i was thinking, cant i just connect it to the 3v pin on the arduino UNO instead of the 5v? will it be the same as putting a resistor on the 5v? thanks

[Reply #1 on:]

You will need the resistors or level shifters for the data lines from Arduino to Display. The power supply can be taken directly from the 3.3V source of the Arduino board.

Oliver

[Reply #2 on:]

It is recommended by some websites

I understand the "some" is because older Arduinos did not have sufficient power available on the 3v3 pin and those sites are outdated.

My 5110s all run off the 3v3 pin and no resistors anywhere except on the backlights. And therein lies a bit of a joke. The backlighting is quite different from my 5110 phone and is so useless that, for anywhere other than total darkness, you might as well leave it disconnected. This particularly applies to the blue backlights. The white ones are a lot better but still poor. 

Here are some useful links

http://blog.stuartlewis.com/2011/02/12/scrolling-text-with-an-arduino-and-nokia-5110-screen/

http://www.carlos-rodrigues.com/projects/pcd8544/

http://code.google.com/p/pcd8544/

[Reply #3 on:]

hi, i saw the link already. thanks alot! really helpful! what is the resistor value recommended for the led backlight?

[Reply #4 on:]

I have a 470ohm with the white light.  Having direct connect doesn't seem to do any harm, probably because there are limiting resistors built-in, but it doesn't help much either. I'm not kidding when I say the backlight is pretty useless.  Indeed "backlight" is a misnomer anyway. The LEDs are not back lighting, they simply put some light on the screen from the sides. I only have blue and white. They are available with red and green but I doubt they are any better.

They are a great little display and I get them because of the nice 6-line text but, if backlighting is important, you are much better off using a 4x20 - which shouts at you from across the street.

Pic shows 5110 with backlight disconnected.

[Reply #5 on:]

hmm looks ok to me...thanks for the advice! your setup lools very good btw!

[Reply #6 on:]

I'm using this hardware set-up: https://www.sparkfun.com/tutorials/300
Powered 3.3 and 5 resistors on data lines:
http://coolarduino.wordpress.com/2013/06/09/function-generator-with-photoresistive-optocoupler/
Though, backlight is always on, otherway display 3.3V power goes up !

[Reply #7 on:]

Hummm... I guess it is best not to ask how that happens.

[Reply #8 on:]

Yea, I know it's getting power from inputs, one of the resistor 1k, and supply about 2mA when driven high. Keeping backlight on is the easiest solution I came up with

[Reply #9 on:]

See? I knew it was best not to ask.