jGPX: display

Yesterday, Chris and I spend the better part of the afternoon trying to make our LCD display (DEM16216SYH-LY) work. While deciding which parts we would need, we concluded (I suppose from the datasheet linked on Watterott, where we bought it) that this type of display is compatible with the well-known and well-supported HD44780. But yesterday, we couldn't get it to display anything. But eventually, we got it right.

Lessons learnt (well, I do hope so):

  • The V0 pin is a strange thing. We thought we were supposed to feed ~4.5V into it, so we adjusted our trimpot accordingly. It doesn't work like that however, so we saw _nothing_ on the screen. Turns out you have to pull V0 down enough until the pixels appear. If you tie V0 to ground, the contrast is to high, if you leave it high, nothing appears. Our LCD is good when we connect V0 to the ground through an 2.2K resistor. The voltage across the resistor is ~0.4V, leaving  ~4.6V for the LCD module. We found about all that after reading this post on a German forum (why yes, Chrome, I would like to translate that!).
  • Datasheets are horrible. We found over 9000 different datasheets for the same component. Different as in completely different initialization methods: from some datasheet it appeared that the Arduino library would work; others told it wouldn't. But it is. Many WTF's were emitted.


1 comment

# chris on 07/27/11 at 19:50
It turns out the datasheet mentions "VDD - V0" as test condition for VLCD - so on second thoughts the "Widerstand musste recht klein sein" should not be a surprise (with or without Chrome).

Welcome to the world of datasheets :-).