这种技术可以在任何Greenpak内使用，带有OE引脚。

通常，GreenPak I / O可以配置为输入或输出。输出使能（OE）引脚是在大多数GreenPak内选择引脚，允许引脚在数字输入和数字输出之间动态地改变（图A）。当OE GPIO设置为永久输入时，OE引脚设置为接地，如果将GPIO设置为永久输出，则OE引脚设置为VDD。将GPIO设置为数字输入/输出允许在矩阵中进行此选择。

Setting a GPIO as a digital input/output allows for two-way communication. It also allows for the GPIO to be set to Hi-Z in addition to a logical high and low.

If the GPIO is used for two-way communication, it’s important to implement a timing circuit for OE selection. In the example circuit below the OE pins of CLK_IO and Data_IO are switched from low to high after CNT2 sees 8 clocks, consequently setting the OE pins as outputs to transmit the internal signals. After another 8 clocks the OE pins are reset low, setting them as inputs again to receive an external signal.

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