BCD to pulses

[Dario0]

Hi,

Somebody knows a simple circuit that convert BCD number to a series of pulses, for example if your input is the BCD 0010 the the result output is 2 pulses (the inverse of a BCD counter).

Thanks.

 

[Reloadron]

You will need to better explain what you want. Do you mean convert a BCD Parallel format to a serial format like RS232 or 422? That would be parallel BCD to serial conversion. What exactly are you trying to do?

Ron

 

[crutschow]

You can parallel load the BCD values into an Up/Down counter (one 4-bit counter per 4 BCD [digit] values) and have the counter count down to zero. The number of clock pulses until it reaches zero is your desired pulse output.

 

[BrownOut]

It's a theoretically simple problem. Use a decade counter ( many are available ) and a magnitude comparator. A clock will be required for counting, and this clock will also be the output of your circuit. The output of the magnitude comparator will enable the outputting of the clock. When the decade counter = the input BCD code, the output is disabled.

 

[Dario0]

Could you please be more specific, I don't get it.

Thanks

 

[BrownOut]

What part do you not get? What's a counter? What is zero? What is "="?

 

[Dario0]

@ crutschow: Could you please be more specific, I don't get it.

Thanks

 

[crutschow]

As BrownOut said, what don't you get?

The concept is quite simple. You parallel load the BCD values into a counter and then have it count down to a value of zero, which you detect and stop the count. The number of clock pulses to the point where the count reaches zero is the pulse output you want.

Of course you will need some logic circuits to perform the parallel load, start the counter, and then stop it at count zero. (You are familiar with counters??)

 

[Grossel]

I think that using a count-down decade counter where you can input bcd directly (or via enable-gates) to "set" input might reduce the numbers of components.

But - you haven't told how to trig it. If any bcd != 0000b should trigger the unit then you also need at least a SR latch that enable on trigger and disable when counter reach 0000b.

And you'll make the question: Will the counter start counting down even if "set" inputs continue being not 0000b?

 

[BrownOut]

I think that using a count-down decade counter where you can input bcd directly (or via enable-gates) to "set" input might reduce the numbers of components.

It might reduce the part that determines when to stop counting, depending on whether one tries to build it with descreete gates or just use a mag comparator. But the control of the "count up" solution is simpler: assert the BCD code at the input to the mag comparator, toggle the reset to the counter.

 

[crutschow]

It might reduce the part that determines when to stop counting, depending on whether one tries to build it with descreete gates or just use a mag comparator. But the control of the "count up" solution is simpler: assert the BCD code at the input to the mag comparator, toggle the reset to the counter.

That works as long as you use BCD decade counters, as you stated earlier. The count down approach can use either a binary or decade counter.

 

[BrownOut]

Disagree. For a single BCD decimal, a binary counter would work either way. For two or more decimals, it fails either way.

 

[crutschow]

Disagree. For a single BCD decimal, a binary counter would work either way. For two or more decimals, it fails either way.

You are correct. I had a brain malfunction.