MCU parallel port expansion and memory expansion-EEWORLD

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MCU parallel port expansion and memory expansion

1. The expansion of the parallel port of the single-chip microcomputer uses the same addressing method as the data memory. There are three methods:

1) Bus expansion: expand the P0 port through a latch. This expansion method only occupies the P0 port in a time-sharing manner without affecting the connection between the P0 port and other expansion circuits.

2) Serial port expansion: The expansion of the I/O port is completed through the working mode of the serial port, which is mostly achieved through the shift register 164/165. It has obvious disadvantages, occupies the serial port, uses the shift method, and has a slow speed.

3) Expand through the on-chip I/O port, that is, expand through other on-chip I/O ports instead of P0 port, such as 8255.

2. MCU memory expansion, including program memory expansion and data memory expansion. Since the program memory and data memory in the MCU are strictly separated, the operation timing of program memory expansion is different, which can be divided into two types: executing MOVX command and not executing. The expansion of data memory is relatively simple, and there are many expansion methods. I will not go into details here.

Keywords：MCU Reference address：MCU parallel port expansion and memory expansion

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