51 MCU basic structure

    ·8-bit CPU·4kbytes program memory (ROM) (52 is 8K)

    ·128bytes data memory (RAM) (52 has 256bytes of RAM)

    ·32 I/O lines·111 instructions, most of which are single-byte instructions

    ·21 special registers

    ·2 programmable timers/counters·5 interrupt sources, 2 priority levels (52 has 6)

    ·One full-duplex serial communication port

    ·External data memory addressing space is 64kB

    ·External program memory addressing space is 64kB

    ·Logic operation bit addressing function·Dual in-line 40PinDIP package

    ·Single 5V power supplyCPU

    : consists of calculation and control logic, as well as interrupt system and some external special function registers;

    RAM: used to store readable and writable data, such as intermediate results of calculations, final results and data to be displayed;

    ROM: used to store programs, some raw data and tables;

    I/O port: Four 8-bit parallel I/O ports, which can be used as input or output.

    T/C: Two timers/counters, which can work in timing mode or counting mode;

    interrupt control system with five interrupt sources;

    a full-duplex UART (universal asynchronous receiver transmitter) serial I/O port, which is used to realize serial communication between single-chip microcomputers or between single-chip microcomputers and microcomputers;

    on-chip oscillator and clock generation circuit, quartz crystal and fine-tuning capacitor need to be connected externally. The best oscillation frequency is 6M-12M.