Author Topic: Newhaven Display Issues  (Read 657 times)

sherloc987

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Newhaven Display Issues
« on: December 08, 2018, 05:59:34 AM »
I am a newbe who is attempting to interface with a LCD for the first time. I ordered three Newhaven 2 x 16 displays, part number NHD-0216BZ-FL-YBW.

I am having some trouble getting the thing to display anything. I was told by a Newhaven engineer that if contrast is set correctly that it will light up the first line when power and ground are connected.

I connected the first one according to the pin lables on the board. it flashed some crazy gunk on the display and then went quiet, never to twitch again. I then noticed that the pin marking do not match the data sheet. Upon contacting Newhaven, I was told that the data sheet was correct and to disregard circuit board labeling.

The data sheet calls for a 10~20K variable resistor. I don't have a variable resistor in the shop so connected several resisters and series. I connected the contrast pin to ground throuh 20K of resistors... no display. I connected it to ground through 10K of resistors... no display. I tried it at resistance levels between 10 and 20 K with no display. Any suggestions will be appreciated

I assume that 10~20K, as indicated in the data sheet means a pot with minimum resistance of 10K and maximum resitance of 20K, is this correct?

Thanks for your help

Lance
« Last Edit: January 24, 2019, 11:31:03 AM by Alee_S »

Alee_S

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Re: Newhaven Display Issues
« Reply #1 on: December 31, 2018, 01:45:16 PM »
Hi sherloc987!

A pot is a variable resistor that can be adjusted anywhere from 0 ohms to the maximum resistance it is rated to handle. So when the datasheet recommends a 10k~20k pot, it means any pot that has a maximum resistance within a 10k~20k range. 

However, the technique you used of connecting a series of resistors together can also yield proper contrast on the display, pending that you attain a recommended rated voltage of 0.5V across Vo (Pin 3), as shown by the electrical characteristics table on pg. 4 of the Datasheet.
http://www.newhavendisplay.com/specs/NHD-0216BZ-FL-YBW.pdf

Since you were using resistor values of 10k and above, chances are your contrast voltage on Pin 3 was too high. I would recommend you try to decrement your value of resistors connected to ground (9k, 8k, 7k, etc.) until Vo approaches 0.5 V, and if everything else is working correctly, you should start to see text appear on the display.

Hope this helps!

Please let me know if you need any further assitance!

 

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