外文翻译--单片机at89c

外文翻译--单片机at89c内容摘要：

und. Port 0 Port 0 is an 8bit open drain bidirectional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high impedance Inputs. Port 0 can also be configured to be the multiplexed loworder address/data bus during ccesses to external program and data memory. In this mode, P0 has int ernal pullups. 设计巴巴工作室 Port 0 also receives the code bytes during Flash programming and outputs the code bytes dur ing program pullups are required during program veri fication. Port 1 Port 1 is an 8bit bidirectional I/O port with internal Port 1 output buffers can sink/source four TTL 1s are written to Port 1 pins, they are pulled high bythe internal pullups and can be used as inputs. As inputs,Port 1 pins that are externally being pulled low will sourcecurrent (IIL) because of the internal pullups. In addition, and can be configured to be the ti mer/counter 2 exte rnal count input () and the timer/counter 2 trigger input(), respectively, as shown in the following table. Port 1 also receives the loworder address bytes during Flash programming and verification. Port Pin Alternate Functions T2 (external count input to Timer/Counter 2),clockout T2EX (Timer/Counter 2 capture/reload trigger and direction control) MOSI (used for InSystem Programming) MISO (used for InSystem Programming) SCK (used for InSystem Programming) Port 2 Port 2 is an 8bit bidirectional I/O port with internal Port 2 output buffers can sink/source four TTL 1s are written to Port 2 pins, they are pulled high bythe internal pullups and can be used as inputs. As inputs,Port 2 pins that are externally being pulled low will sourcecurrent (IIL) because of the internal pullups. Port 2 emits the highorder address byte during fetches from external program memory and during accesses toexternal data memory that use 16bit ddresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pullups when emitting 1s. During accesses to external data memory that use 8bit addresses (MOVX @ RI), Port 2 emits 设计巴巴工作室 the contents of the P2 Special Function Register. Port 2 also receives the highorder address bits and some control signals during Flash programming and verification. Port 3 Port 3 is an 8bit bidirectional I/O port with internal Port 3 output buffers can sink/source four TTL 1s are written to Port 3 pins,they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups. Port 3 also serves the functions of various special featuresof the AT89S52, as shown in the following table. Port 3 also receives some control signals for Flash programming and verification.。