| 摘要 |
PURPOSE: A programmable input/output circuit is provided to delay a drive signal to supply the delayed signal on an output driver with a time difference, and to control the output driver and to change the port type by implementing plurality of output transistors in the output driver. CONSTITUTION: The programmable input/output circuit includes a drive signal generator(300), a delayer(400), a port type setter(500) and an output driver(600). The drive signal generator(300) logically combines the output signals of the input/output set register for setting input/output and a port data register for outputting data. The delayer delays the output of the drive signal generator for a predetermined period of time. The port type setter(500) outputs a port type set signal with response to the output signal of the drive signal generator, reset signal, shift clock signal and a port type signal from outside. The output driver(600) outputs the data in CMOS type or PMOS open drain type with response to the output signals of the port type setter and the delayer.
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