Sequential Circuits

Q: Serial Data Transfer

Q- Design a circuit to transfer data serially from one shift register to other.

Ans:  If we have a N-bit shift register then we need only N clock cycles to shift those N-bits to the other register. If we apply more or less than this many clock cycles then our operation of shifting would not be as required. Hence we have to give a control pulse which would control that only N clock cycles are given to the registers. The circuit diagram is as follow: 

If we are to transfer data between 4 bit register then control pulse would be 4 clock cycles wide as shown so that only 4 clock cycles are passed.

Following table would show the values of two registers at different clock cycles

Register 1                            Register 2            Output

                                            1101                                       1001

First clock                            1110                                       1100                       1

2nd clock                              0111                                       0110                       0

3rd clock                               1011                                       1011                       0

4th                                        1101                                       1101                       1

Hence we see that register1 retains its contents and register2 gets the value of register2 which was required.

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