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Counter IC

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jonathand1000

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Hi,
Does anyone know of a counter IC where you can set a 4 bit number on the right, and making clock high on the left increments another number, but resets when it gets to the number on the right? (obviously, right/left or whatever). I know I can do this with logic gates and a 4518B or something, but it's just that for my GCSE Design my teacher reckons my circuit should be simpler, and I'm tryin to cut down on ICs.

Jon

My opinion: You need a programmable down-counter, e.g. CD4522.

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Thanx alot, that's a great help. There's just one thing though, is there a version of this chip where P0-3 can also be clocked? I tried a search on the net, but couldn't really make much sense of the mass of information and long lists of chips that came up!

Jon

P03?

I don't understand your question. What are you trying to do that Sebi's circuit doesn't?

Hi,
sorry I haven't replied too quickly, my computer broke down...anyway, I'm making a metronome, and I want, every few beeps, to have a higher frequency beep. This counter sets the number of low beeps between each high beep. eg if H=high and L=low, pattern when counter is set to 0 is LLLLL, =1, HLHLHLHL, =2, HLLHLLHLL and so on. THe chip above will not (I don't think?) allow both the counter and the bit where you set the number on the left to be incremented. The aim of integrating this chip into the circuit is to actually reduce the number of ICs in the circuit overall, and if I use the CD4522 as suggested by Sebi, I will need a seperate BCD counter to control P inputs P0-3. I was just wondering if there was another, similar chip, where A clock input had been integrated to increment P0-3 by 1 whenever it went high.

Jon

metronome counter

ok, I see. You basically want a second 4-bit counter driving the parallel load inputs. Due to pin limitations (16), standard MSI counter ICs usually have either a 4-bit parallel load feature (xx161, xx193) or two 4-bit counters (xx393, xx4520), i.e. 4 pins are used as inputs or outputs. You're looking for something like a 4520 with the second counter internally loading off the first counters' output, and I'm not aware of any standard chips that do this.

- CAL

btw, the CD4522 seems to be available on the surplus market, and it's operation looks straightforward, but I couldn't find a datasheet for it online. You might consider another variety of 4-bit counter, like the 74HC193, but Sebi's got the right idea.

Thanx alot, that's a great help. There's just one thing though, is there a version of this chip where P0-3 can also be clocked?

I think what you mean is a external load input ability rather than clocking. A 74193 as a load input pin (LD) that is used to load an external nibble but this is usually syncronized with the clocking signal via a gate.

You must also realize that once an external nibble is loaded into the counter the counter will continue counting from what ever the loaded nibble was, regardless of what the count was originally. In other words an externally loaded input can advance the counter or vise versa.

Nettron, the way the question was worded confused me at first, but I think jonathan wants to advance the nibble value going in to the parallel load inputs with a clock. Sebi's circuit already uses the parallel load feature of the 4522 when the terminal count (0) is reached.

Jonathan, the 74xx161 or 163 do pretty much the same thing, except they're up-counters, so the terminal count is 15. Their TC outputs need to be inverted if you're going to use it to drive the parallel enable input. The 74xx193 is a little more flexible, being an up/down counter. It has TC outputs (active-low) for both directions.

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