Development Board Components

Additionally, with the switch in the RUN position, the Quartus II Programmer can program the FPGA directly through the USB Blaster circuit. With the switch in the PROG position, the Quartus II Programmer can program the EPCS4 device.

Push Button Switches

The development board provides four push button switches, KEY0-KEY3, located at the bottom right on the development board below the green LEDs, LEDG0-LEDG7 (Figure 2–10). The momentary-contact switches provide stimulus to designs in the FPGA.

Figure 2–10. Push Button Switches and Green LEDs

A switch generates an active-LOW pulse at 0 volts when pressed, returning to a HIGH logic level at 3.3 volts when released. A Schmitt Trigger circuit on each switch debounces the signal (Figure 2–11).

Figure 2–11. Switch Debouncing