I have the following LCD: http://www.xmocular.com/Upload/CMpdf/GDM1601C-01010742776.pdf

I am trying to hook this up to my Teensy. I assume that because it has 16 pins that it's a HD44780 display. Am I correct?

I'm following this guide to hook up the LCD to the Teensy: https://wiki.natenom.com/w/Connecting_a_Teensy_3.0_to_a_LCD_(HD44780_display)

The problem I'm having is I'm getting nothing on the screen. I have a pic of my breadboard but it's probably mostly useless: http://imgur.com/cepm6p6

I don't quite understand where the pins from the LCD should be going into the Teensy - I followed the guide. I noticed that pin3 is the contrast, but on the guide pin3 is going to a digital pin on the teensy. I'm not sure if that's correct.

What could I be doing wrong?


1 Answer 1


That's a bad assumption. Just cause it's 16 pins doesn't mean it's a HD44780 display. Of course, this one is, but that's not a good assumption to make. The datagram says:

Built-in controller (KS0066U or Equivalent)

That's basically the same as HD44780.

The contrast pin should be tied to ground. The guide has it tied to ground. The pins on the guide are left to right. Instead, follow the pin out on the data sheet. Don't assume your lcd has the same pinout as the guide.

  • \$\begingroup\$ Good advice, thank you. I followed the data sheet and managed to get it all set up correctly. I put contrast to ground. Problem is all I see is dark squares (only half of the display). \$\endgroup\$ Commented Jan 22, 2017 at 20:38
  • \$\begingroup\$ That's a code or timing problem then. The display is not initializing properly. \$\endgroup\$
    – Passerby
    Commented Jan 22, 2017 at 20:43
  • \$\begingroup\$ I'm following the code from the guide. I've tried all sorts and am convinced the LCD is faulty. When I connect the backlight nothing happens. \$\endgroup\$ Commented Jan 22, 2017 at 22:18
  • \$\begingroup\$ Are you sure you bought the 5V version? Or a version with a back light? There is a led version a el versión and a non back light version. \$\endgroup\$
    – Passerby
    Commented Jan 22, 2017 at 22:20
  • \$\begingroup\$ I'm not sure if it's the LED version. I found it in an old box of electronics bits I had from 2006. It is the 5V version because it says in the data sheet. \$\endgroup\$ Commented Jan 22, 2017 at 22:29

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