I was messing up with a project lately where I needed dual alphanumerical LCD displays.┬áThe plan I had was parallelling them, so I searched the internet about it and couldn’t find anyone that has practically did that, other than that I saw people asking about it at StackExchange.

Then I thought about it and I gave it a go. The result is positive! However, there is a gotcha; if you are using LCDs from different manufacturers or different types, the contrast setting might differ, as it did in my example. In order to overcome this, I would suggest putting two potentiometers in your board to adjust the contrasts individually. And don’t forget, you are using one more LCD, meaning more back light current. If you are using a 7805 without a heat-sink, you should re-calculate your thermal values.

Here is the result:

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    4 Thoughts on “Paralleling LCDs? No problem!

    1. aleza on March 1, 2013 at 15:05 said:

      The 2 lcd show the same data? Does it work with lcdproc?

      • Yes, as you can see, they are showing the same data. This is possible as long as they have the same chipset, which is almost all cases. I don’t understand what you mean by “lcdproc”.
        However, this method is firmware independent, meaning that if your software works for one of the LCDs, then it will work after you parallel them, too. However, check the electrical specifications of the LCD and your microcontroller.

    2. I manged to address the LCD’s individually, so I can write different content to each LCD:
      http://mcuoneclipse.com/2014/01/02/character-lcd-with-4-lines-and-up-to-64-characters-per-line/

      I have found that way while developing a driver for a 4-Line LCD :-)

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