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Topic: Nokia 5110 display strange behavior while powered at 5V  (Read 89 times) previous topic - next topic

numlo

Hello,

My Nokia 5110 display does a strange thing when I power it at 5V with 5 10K resistors on the data pins. It's this setup: http://ianlangelectronic.webeden.co.uk/#/lcd-module-0/4569058582

Sometimes the display works fine. Other times it does some kind of flicker. It's like horizontal waves that run in the background. Sometimes it's barely noticeable and sometimes it's really annoying. Depending on the angle I am looking at the display, the waves are more or less visible. Text appears without any problems.

When used with a 4050 at 3.3V the waves are gone and everything is working fine.

Does anyone have an idea about this problem? It's easier for me to use it at 5V and I would like to find an answer to this problem.

Does it matter if the Arduino pins connected to the display are PWM pins or not?

avr_fred

Why is it easier for you to use the incorrect voltage?

Did you overlook this line from the tutorial you linked to: VCC which is the positive and needs 3.3V

When the tutorial says use 3.3 volts supply, why do you ask "how do I make it work at 5 volts" ?

Some of these displays do need a bypass capacitor on the VCC to GND terminals to avoid distorted output. But, do not assume this will resolve your use of the display at 5 volts. It is a 3.3 volt device. Using it at 5 volts will most likely result in an early death.

Oh, yes, your last question. No, PWM pins are only PWM when you write to them with an analogWrite() function call. Otherwise, it's just an ordinary digital output.

Nick_Pyner

Some of these displays do need a bypass capacitor on the VCC to GND terminals to avoid distorted output.
@ avar_fred.
Sorry for hijacking this thread, although it may be construed as resurrecting it, but what sort  of distorted output are you referring to?

My 5110s are fine now, using the PCD8544 library, but my early attempts were not too encouraging. I have seen the "waves" too. This was particularly evident with bold fonts where there also seemed to be bleeding between characters. None of the graphic demos I saw were worth bothering with.

avr_fred

No worries Nick. The information on bypassing turned up during my research to confirm that there indeed were no 5 volt variants out there. I have personally never seen the distortion but then I have only used two of the displays - so my exposure is limited. In retrospect, given the OP's questions, I should not have mentioned bypassing.

In my haste to post, I guess I fell victim to the classic "if it's on the Internet, it must be true".

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