单片机毕业设计AT89C51 应用说明.docxVIP

AT89C51 PLAYBACK DEVICEThe features of AT89C51 are: Compatible with MCS-51；4K Bytes of In-System Reprogrammable Flash Memory；1,000 Write/Erase Cycles；Fully Static Operation: 0 Hz to 24 MHz；Three-level Program Memory Lock；128 x 8-bit Internal RAM；32 Programmable I/O Lines；Two 16-bit Timer/Counters；Six Interrupt Sources；Programmable Serial Channel；Low-power Idle and Power-down Modes。 Description：The AT89C51 provides the following standard features: 4Kbytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bittimer/counters, a five vector two-level interrupt architecture, a full duple serial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt sys -tem to continue functioning. The Power-down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.Pin Description：VCC：Supply voltage.GND；Ground.Port 0：Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1sare written to port 0 pins, the pins can be used as high impedance inputs. Port 0 may also be configured to be the multiplexed low order address/data bus during accesses to external program and data memory. In this mode P0 has internal pullups. Port 0 also receives the code bytes during Flash programming, and outputs the code bytes during program verification. External pullups are required during program verification[7].Port 1：Port 1 is an 8-bit bi-directional I/O port with internal pull ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal