A counter is a circuit that counts the number of occurrences of an input. The circuit consists of flip-flops which along with combinational elements are used for generation of control signals.
If M = Total number of states, and n = Total number of flip-flop Then, M <= 2n If M = 2n ; Binary counter and M < 2n ; Non-binary counter
Block Diagram of Non-Binary Counter:
Here is the block diagram of a mod-10 counter. Here, the total number of flip-flops required is 4 thus the number of used state is 10 and number of unused state is 6.
In order to design a non binary counter a logic gate is required which detects M stage. In mod-10 coounter 10 stages are detected from 0000 to 10001 and as soon as 1010 appears it clears all the flip-flops.
Making of Non-binary counter:
For making non-binary counter,
- If CLR is present and CLK is connected with output Q, then we use AND gate.
- If CLR is present and CLK is connected with output Q’, then we use NOR gate.
- If complement of CLR is present and CLK is connected with output Q, then we use NAND gate.
- If complement of CLR is present and CLK is connected with output Q’, then we use OR gate.
It is clear from truth table that as soon as 1010 appears, inputs to the AND gate becomes 11 which resets the flip-flop with CLR =1.
The output frequency of mod-M counter,
= f / M
If there is no feedback present at last output (i.e D) then the output frequency,
= f / (2n)
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