The Quad General Purpose Input/Output Card provides four connections to the FPGA. The output is 3.3 volts and the input can range between 3.3 and 5 volts. This card is often paired with the "gpio4", "in4", or the "out4" FPGA peripherals. The GPIO4 card is also used with the dual quadrature decoder ("quad2"), the quad event counter ("count4"), the quad PWM input ("pwmin4"), the quad PWM output ("pwmout4"), the quad Ping sensor interface ("ping4"), and the quad servo controller ("servo4") FPGA peripherals. Click here for more information.