/diy/ - Do It Yourself

>>1297962
Well I'm using an Arduino to turn my 3-digit (measured temperature) value into some 7-seg + adjust-LED serial list and feeding that out through a single output into three 74HC595 latching shift registers, plus a clock to shift all the inputs through the three registers and another 1/24th speed clock to latch them all every full cycle. It's not going to be easy to program, but it's the method that takes the least amount of ICs and output pins.

For your purpose using a micro isn't terribly desirable, but it isn't all too expensive if you go with a knockoff. I'd personally see about doing it with a bunch of flip-flops to make a set of frequency dividers for each digit, plus some logic to get them to overflow from 9 to 0. That takes 16 flip-flops all together, so your best bet is 4 74276 (or something similar) quad flip-flops with seperate clocks. What can I say, I'm a sucker for the 7400 series. Note how the three animated flip-flop outputs count upwards in binary (from left to right). Then use any old NAND/NOR IC to implement the return condition, and put whatever BCD to 7-seg IC on the output of each digit. Figuring out how to count downwards might be difficult, but you can mess around to no end in Logisim until you figure something out.

Read up on basic logic gates (xor/xnor is optional, nobody uses them anyway), boolean algebra, Karnaugh maps, latches, flip-flops, and maybe shift registers.