74HC595D is a general purpose LED driver chip with 8-bit latch, 8-bit serial input, 8-bit string\/parallel output, series-parallel shift register and three-state output functions.
It is used as follows:
The data first passes through the shift register, then latches into the storage register, and finally the data is output in parallel when the OE pin is low.
Drive 74HC595 mainly controls SHCP, DS, STCP, MR, OE five pins.
When the cascade function is used, the 10th, 11th, and 12th pins of all 74HC595D are connected to the pins of the main control chip, and the 9th pin of the U27 is connected to the 14th pin of the U26 to form the cascade function.