problem in a circuit

[Rajafaisal09]

Hello to every1 well i m facing a problem in circuits ..question is

*) Draw a Circuit diagram of a diode matrix to encode 4 input lines of BCD information into a binary count of a 4 stage register ?

well send me the ckt plz at faisal_rjazz@hotmail.com

n plz a bit of description if u can

 

[ljcox]

I don't understand the question.

Do you mean you want to encode 4 input lines into binary, ie. a "one of 4" to binary conversion?

Len

 

[Rajafaisal09]

well i want a diode constricted diagram tht convert 4 lines of input of BCD code in to binary counter .....ur first option

 

[ljcox]

Your description
"convert 4 lines of input of BCD code in to binary counter"
still does not make sense.

BCD means "binary coded decimal", but you appear to be wanting to convert "one of 4" to BCD.

The attachment is what I assume you want. If not, please explain in more detail. A diagram would help.

Len

 

[Rajafaisal09]

well i want a circuit tht should convert BCD to binary simple

 

[ljcox]

What is confusing me is that 4 bit BCD is binary.

BCD Binary
0000 0000
0001 0001
0010 0010
etc until 9, i.e.
1001 1001

If there are 2 or more BCD digits, then you have to convert BCD to binary.

I posted a circuit to do this on March 9. See "Converting BCD to Binary using combinational logic" in Electronics Chat

Len

 

[ljcox]

The principle of how to convert BCD to Binary is illustrated in my post quoted above. But in that case, the enquirer only wanted to convert numbers between 00 and 31 (ie. day of the month digits)

Binary = U + 10 * T + 100 * H + 1000 * M where U = the units digit in BCD, T = the tens digit, H = the hundreds digit and M = the thousands.

So in the circuit quoted, I converted the Tens BCD digit to 00, 10, 20 or 30 depending on the BCD tens digit and then added it to the units digit.

So to cover the full range of tens digits, you will have to design logic to do this conversion (ie. if the tens BCD digit is 4, generate 40 in binary and input it to the adder, etc). Repeat the exercise for the Hundreds and Thousands digits. Then add them all together.

Another way to do it would be to use 4 presettable decade counters (configured to count down) and a binary counter (configured to count up). Preset the decade counters with the BCD digits and reset the Binary counter. Then apply clock pulses to both counters. When the Decade Counter = 0, stop the counting and the binary counter will indicate the binary value of the BCD digits.

Len