On this page, I will introduce a latch register for "Signboard 2" using PIC.
This is the latch circuit for the LED of the signboard.
There is a latch register by the general logic IC(Like 4034B : 8 Bit Universal Bus Register).
To latch with 8bits x 16rows, 16 pieces of IC are needed. Their IC is 24 pins generally.
To mount them, a lot of space is needed.

The circuit to introduce here is the circuit which used two CPLD(XC9572-PC84).
In one CPLD, it is made to have the latch function of 7 bits x 8rows by the limitation on the number of the pins.

The binary code of 4 bits is used for the selector to specify a row.
Each IC has 4-16 selector. It controls eight rows which are different in each IC.

Side A Equivalent circuit Source code/Explanation Fitting report Side B Equivalent circuit Source code/Explanation Fitting report

Operating state table Input Output CLK S0 S1 S2 S3 Q0-Q15 0 0 0 0 Q0 = DIN 0 0 0 1 Q1 = DIN 0 0 1 0 Q2 = DIN 0 0 1 1 Q3 = DIN 0 1 0 0 Q4 = DIN 0 1 0 1 Q5 = DIN 0 1 1 0 Q6 = DIN 0 1 1 1 Q7 = DIN 1 0 0 0 Q8 = DIN 1 0 0 1 Q9 = DIN 1 0 1 0 Q10 = DIN 1 0 1 1 Q11 = DIN 1 1 0 0 Q12 = DIN 1 1 0 1 Q13 = DIN 1 1 1 0 Q14 = DIN 1 1 1 1 Q15 = DIN CLK is effective when changing into L from the H.