Design a display for watch which will show the number of days in a month. Thereisakeypadwith1to12inputbuttons . Thekeypad’s12outputlineisconnectedt otheinputof‘A’block.‘A’blockoutput’ s4bitbinarynumberwith4outputpinswhi chisconnectedtothe‘B’blocksmonthinp ut.‘B’blockoutputs4bitsrepresenting thenumberofdaysinamonth. Thereisaseparateinputforleapyearin‘ leap’pin.

An BCD-to-seven-segment decoder is a combinational circuit that converts a decimal digit in BCD to an appropriate code for the selection of segments in an indicator used to display the decimal digit in a familiar form. The seven outputs of the decoder (a, b, c, d, e, f, g) select the corresponding segments in the display, as shown in Fig. (a) . The numeric display chosen to represent the decimal digit is shown in Fig. (b). Using a truth table and Karnaughmaps, design the BCD-to-seven-segment decoder using a minimum number of gates. The six invalid combinations should result in a blank display.

Design a circuit to display the number of days using 7 segment display.
In Part –A, the output from ‘B’ block will be fed to 2 decoders. One decoder(C_a) will provide the units digit BCD and the other(C_b) will provide the tens digit BCD. These will be fed to a BCD to 7 segment decoder designed in Part –B to drive the 7 segment displays. Design the necessary C_a, C-b blocks.