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I recently obtained DEM 16217 SYH-PY 2x16 character screen. Here's the datasheet. As far as I can see, its contrast pin should be connected to voltage source over a potentiometer. How do I pick correct resistance of the potentiometer for this use?

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  • \$\begingroup\$ Wheres the datasheet? \$\endgroup\$ – Dean Feb 12 '11 at 21:56
  • \$\begingroup\$ @Dean For some reason, it wouldn't let me link directly to file. I linked now to the list of the datasheets for their displays. \$\endgroup\$ – AndrejaKo Feb 12 '11 at 22:05
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I don't think it makes a whole lot of difference. I've used a 10KΩ linear before which works perfectly well.

You're essentially making a potential divider, connecting your pot between your supply and ground, so as long as it's not too low value that it starts to draw more than a negligible amount of current.

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  • \$\begingroup\$ OK. I'll try with that, once I obtain suitable potentiometer. \$\endgroup\$ – AndrejaKo Feb 12 '11 at 22:06
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I'm working with RT162-7 based on HD44780 (seems compatible to your DEM 16217 SYH-PY).
Connecting the contrast pin (V0) directly to 0 gives very reasonable contrast, even without a potentiometer or a potential divider.

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  • \$\begingroup\$ Most HD44780 LCDs work reasonably well with 0V for constrast, but some will definitely work better (may depend on viewing angle) with a slightly higher voltage, so it is a good idea to include a simple potmeter. (and there are of course LCDs, esepcially wide temperature ones, that require a negative constrast voltage) \$\endgroup\$ – Wouter van Ooijen Jan 21 '12 at 17:46

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