2 Bit Synchronous circuit that operates only with clock [Q]

Question

I am attempting to make the following digital telephony circuit by applying Time Division Multiplexing(TDM).

I am having trouble figuring out how to create a 2-bit counter that counts from 0 to 3, adding one at a rising edge of a clock, and then resets the count to zero and so on.

The 2-bit counter will act as the selector line for the MUX, DMX, and the 2-bit decoder.

I am planning on implementing a synchronous J-K Flip-Flop, but it requires two inputs (J and K) in addition to the clock. According to the diagram below, the only input into the counter and that runs the counter is the clock. So how can I implement a J-K without needing the J-K inputs and only needing the clock, or is there a better flip-flop / latch that can be used? Note I am only 2 weeks new to digital circuit design so don't know much..

Answer 1

There are all sorts of ways.

JK

^{simulate this circuit – Schematic created using CircuitLab}

T (essentially a JK with both inputs tied together

^{simulate this circuit}

D (Essentially a JK with the K inverted, and both tied together)

^{simulate this circuit}

Note that the JK implementation ties the inputs of the first FF high, and this is not shown as an input on most counters.

Answer 2

This is the most common way using a 74HC74

But since not only do you need a 8KHz clock and 2 bit counter , you need a 24 channel counter to decode 1st time slot which is usually done with a CD4020 and gates for /24 for DS1 or use binary addressable 1 of 24 port MUX