| 摘要 |
PURPOSE: A communication interface circuit using a dual port memory is provided to decrease a volume of a circuit and a load of a communication program of a personal computer by performing a communication using a 16-bit address through a command strobe for recording a memory and a command strobe for reading a memory using a dual port memory. CONSTITUTION: The first decoder(102) decodes a control signal being supplied from a personal computer and outputs a signal(/MDPM) for accessing an input/output(I/O) selection signal(/ICS), a memory chip select signal(/MCS), a read signal(/IRD) and a write signal(/IWR), chip select signals(CS1,CS2) and a dual port memory. The first, second, and third buffers(104,106,108) perform a buffering and outputting of data for controlling an external device inputted through a bus from a PC by an enable signal being outputted from the first decoder(102), and perform a buffering and outputting of the address inputted through the bus, the input/output chip select signal(/ICS), the memory chip select signal(/MCS), the read signal(/IRD) and the write signal(/IWR) outputted from the first decoder(102). The second decoder outputs the memory reset signal for accessing a dual port memory by a control of the external device, interrupt requesting signals, a chip select signal and a bus busy input signal. A dual port memory records data transmitted from the PC by a write signal outputted from the third buffer and reads the data and records data transmitted from the external device and reads the data for communicating the PC with the external device. An input buffer receives a signal being inputted from a sensor of the external device and performs a buffering and outputting of the signal. An output buffer receives a signal being inputted from the PC and performs a buffering and outputting of the signal.
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