Help with Dice using a 555 and 74ls(90,190)

Please help! I need to build a circuit which simulates two dice rolling. The user must first hit a logic switch and the dice begin to roll, they hit it again and they stop. If the dice roll a double six, then an led flashes at 4hz using a 555 timer. I know I'll be using a d flip flop in toggle to start and I think I know how to wire up my 555 timer but I am lost with the rest.

Is the led the only output from the circuit? Or do you have 12 LED's for the dice arranged in the same way as the dots?

Sure, a flip flop can make a 'start/stop' button for it, and you can use the 'reset' pin of the 555 to control when the LED flashes. But you would need a fair bit of logic to visually simulate a dice roll, and you'd need AND gates to detect a double-six - at least 8x 2-input AND gates (you can of course get 3,4, or 8 input AND gates as well, you'll have 12 inputs).

Is that what you are trying to achieve here for tyhis assignment?

Blueteeth

the displays are actually two seven segment hex displays, would I still need that many and gates?

If I undestand you will need 3 timmer signals because you have 2 Dices and if you put one timmer signal for the 2 of them your results wil be like 2,2 3,3 4,4 etc...

If this is the case you will need to connect 2 diferent timmer signals to each counter. and for turning on the led in the case you have 2 six's on the dices then you can do that with 1 binary comparators conected to each councounter. You will have to stablish 6 as default number in the comparators. when you got a 6 and a 6 on the dices the comparatos will turon on the pin ''='' and with a logic gate turning evry time the inputs are one and one then you have the signal for turning on the 3 timmer.

Hope this help

Here is a digital dice that I built some years ago.

It only needs one oscillator since the counters are in tandem.

The readout is by LEDs arranged like a real die.

It can be switched to act as one die or two dice.

hegotdajacks said:

the displays are actually two seven segment hex displays, would I still need that many and gates?

Click to expand...

Depends on what you mean by 'many'

7-seg displays are probably easier to work with anyway, as you can get logic decoder chips where you put in a binary number, and it converts it to the pattern for the display.

Chips to consider:
74HC46,74hc47,74hc48,74hc49 (HCT would also work)

cmos:
4026, 4056, 4511, 4543

Seeing as how you'll need two dice, each one would need its own decoder, and binary counter, and timer. And because it only counts up to six, you'll need a form of reset circuit. Finally the 'double six' led would need AND gates on the binary counter outputs, like I said before, except, if you're using a binary counter, a '6' appears as 0110, so each 'die' would need a single AND gate. Then both those outputs AND'ed together would only go high when theres a double six. Sorry if that sounds complicated, I'm not too good at explaining things, are you sure you have to do this in pure logic? Or are you allowed to use PIC's or possibly specific IC's? If you need a rough block diagram, I'll knock one up in MSpaint

Blueteeth

Ps: Wow len, nice circuit, I drew a quick one up when I thought he meant single LED's, very similar layout, same chips too

Blueteeth said:

Seeing as how you'll need two dice, each one would need its own decoder, and binary counter, and timer. And because it only counts up to six, you'll need a form of reset circuit.

Click to expand...

1. By "timer" I asume you mean an oscillator. He only needs one oscillator.
2. It needs to count from 1 to 6 so it needs a preset, not a reset.
3. There is no need for a "power on" reset as the counters will count into the right sequence after a few clock pulses.
4. My circuit could be modified to employ 7 seg decoders to drive 7 seg displays.

Blueteeth said:

Finally the 'double six' led would need AND gates on the binary counter outputs, like I said before, except, if you're using a binary counter, a '6' appears as 0110, so each 'die' would need a single AND gate.

Click to expand...

A 4 input NAND gate would do the job. Connect outputs Q2 & Q3 from both counters to the gate inputs.

Blueteeth said:

Blueteeth
Ps: Wow len, nice circuit, I drew a quick one up when I thought he meant single LED's, very similar layout, same chips too

Click to expand...

Thanks