Big Time Character LCD Clock

While the SSD1306 OLED has somewhat become the go-to display for up-to-date projects, the good old character displays with their Hitachi HD44780 controller don’t seem to be disappearing just yet either. And why would they, especially if you want to show just text, having a built-in font has certainly its perk compared to worrying about integrating your own characters — which you can still do on top as well. Or perhaps you can combine both worlds, which is what [oldmaninSC] did with his digital clock that takes an entire 16×2 LCD to show each single digit.

The whole clock uses 16 individual, upright rotated 16×2 LCDs that are arranged in two rows of eight LCDs each, turning the entire construct sort of into a giant 8×2 display itself. For some additional information such as the date, there’s also a smaller font available that uses only half the height, allowing up to four total rows of information. To communicate with each LCD via I2C, two TCA9548A I2C multiplexers are connected to an Arduino, along with an RTC to keep track of the time and date itself.

As the TCA9548A has three pins dedicated to define its own address, the entire clock could be scaled up to a total of 64 LCDs — so how about a 16×4 display made out of 16×4 displays? Sure, adding smooth scrolling might become a bit tricky at some point, but imagine playing Tetris on that one!

9 thoughts on “Big Time Character LCD Clock

  1. I wired up a character LCD to replace the guts of a old $10 digtal clock. I found out how limited the viewing angle was and have to make do with 7 segment LED. The viewing angle when you rotate it by 180 is going to be worse.

    OLED would have been fine except for their limited life.

  2. I have pondered this sort of thing for years as I have crates (over 1k) of hd44780 LCDs. I was thinking of using them for each segement in a 7 segement arrangement though, filling with characters to “light” the segement.

    1. Aww, so jealous, here it was hard to get those things at a reasonable (sub $50 per unit and nevermind the damn shipping) price while I was interested in them (or rather had the time and energy to spend playing with such things)

  3. This is a superb article, an astounding example of ‘thinking outside the box’, and a great way to kick-start some needed, new life into clock design and build.
    I’ve got several (many) 16 X 4 displays, and am getting started, right now.

    How do I get an article published?

  4. To “correct” the character aspect ratio this thing is SCREAMING OUT for 4×20 LCDs instead of those 2×16 LCDs. Yeah the 4×20 LCDs with I2C/TWI backpacks are roughly twice the price of the 2×16 modules, but I think the improvement would be worth it. As for the viewing angle, a lot depends on the LCD manufacturer and color. I have some white on blue LCDs that have a much wider viewing angle range compared with black on yellow or green. The white on blue seems to use a “negative” or “inverted” pixel scheme, which may help.

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