Recently, I bought this: http://www.sureelectronics.net/goods.php?id=1121 It is described as a "HT1632C-based 32*8 LED dot-matrix info board".
I have had trouble finding a suitable library for this thing. Yes, I have seen Gaurav Manek's library. It is set up in such a way that the fonts hog RAM. This, I guess, explains the small font size he uses. One Nicolas Cortot has modified Mr. Manek's library so that it hogs PROGMEM instead of RAM. Since we have more PROGMEM than RAM to play with, I guess this is all right. Luca Dentella has written his own functions for these displays. I say "functions" rather than "library" because of how they appear in his example sketches. It seems that each of those sketches is designed as a stand-alone proof of concept. It does not appear straightforward to modify or combine the sketches.
What I am trying to do, ultimately, is make a clock using one of these. I am not asking for code or advice for the "timekeeping" portion of this: I think I already know how to do that. What I am looking for is advice on making it look pretty. My inspiration is the clock in this video: http://www.youtube.com/watch?v=pyBAcJHM4Is I want to do better, though. I want to have multiple fonts and be able to switch between them. I want options for different time formats, some with and some without seconds. For this I want to be able to combine fonts: for example, a large font for the hours, a slightly larger one for the minutes, and a tiny one for the seconds. I will also want to be able to make partial fonts: why should I have to draw more than a set of figures if that's all I want? Conversely, I want to be able to display lowercase if I so choose: neither Mr. Manek's library nor Mr. Cortot's fork appears able to handle this. There does not seem to be any facility for combining fonts in a single string, for a scrolling message, for example. However, one thing that is not a problem is displaying changing scrolling text: when showing the time with seconds as part of a scrolling message, for example. You just have to make sure that the relevant characters (in this case, the figures for the seconds) are all the same width.