Programmable 8-character LCD module and digital voltmeter


A programmable 8-character LCD module and digital voltmeter project from Tuxgraphics:

Our 3 digit LED digital voltmeter module has been quite successful over the years. This new LCD module is basically an advanced version with a lot more capabilities. You can power it with the same voltage source that your signal is derived from. You can load your own code into this module but it has even some nice features for people who just need a voltmeter module and don’t want to play with C-code.

Project info at Tuxgraphics.

Files and source code are available at

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  1. This line in their site confused me for a moment: “This module is not just a display. It has as well a dot-matrix area where your can add your own components.”
    Uh, programmers getting the terminology wrong. They are talking about the prototyping area… Though one can also add custom characters to a HD44780-based display to simulate dot-matrix graphics…

  2. Men, just a generic HD44780 LCD and a ATMega328P DIP AVR. Looks like it is running on internal RC clock and no boot loader. Kit doesn’t come with a DIP socket. 15.50 Euros (almost $17.50). Nicely documented though. If they went a little bit further and made it Arduino compatible, I think there would big a much bigger take-up.

  3. The LCD is not _that_ generic… an 8×1 w/backlight is probably more expensive than an 16×2 w/backlight, just try searching in Aliexpress and count the hits and look at the pricing. Plus, they used an LCD part with a FFC/FPC connector and cable, whoa. Gotta be expensive, that.

    They also claim “12 bit with oversampling” (using the AVR 16x oversampling app note). But I wonder how many of their users will _really_ understand the many error sources that will affect their beautiful 12-bit resolution output…

    1. You can’t get 12 bits out of 10 bits without some proper noise or dithering.
      See: “AVR121: Enhancing ADC resolution by oversampling” That’s the thing they used (it’s in the source code) but would you be _really_ getting 12 useful bits in this kind of application? Hmmm…
      Then you can’t extend ADC specs out to 12-bits. Then there is the reference voltage. Maybe I should just put it instead as, 12 bits, with condiments…

      Me, I’d be pretty happy with 10 bits. Once, a car battery tech tried to impress me with getting readings from a lead-acid battery using a 4.5 digit multimeter. Rolled my eyes…

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