来自http://www.altera.com/literature/hb/cyclone-iv/cyiv-51006.pdf

I/O口特性

1.可编程电流强度；

2.摆率设置；

3.漏极开路输出；

4.总线保持；

5.可编程上拉电阻；

6.可编程延时；

7.PCI钳位二极管；(保护IO口使输入电压低于GND-0.7V,高于VCC+0.7V时钳位)

8.支持OCT(on-chip termination)（阻抗匹配和终端电容）;

 

 

9.I/O标准的终端方案

10.Voltage-Referenced I/O Standard Termination

11.Differential I/O Standard Termination

I/O banks

I/O pins on Cyclone IV devices are grouped together into I/O banks. Each bank has a
separate power bus.

                                                                                                                                         所有的I/O默认都是高电平​