Using The Leds And Switches - Altera DE2-70 User Manual

position and then reset the board by turning the power switch off and back on; this action
causes the new configuration data in the EPCS16 device to be loaded into the FPGA chip.
USB Blaster Circuit
USB
Quartus II
Programmer
AS Mode
In addition to its use for JTAG and AS programming, the USB Blaster port on the DE2-70 board
can also be used to control some of the board's features remotely from a host computer. Details that
describe this method of using the USB Blaster port are given in Chapter 3.

5.2 Using the LEDs and Switches

The DE2-70 board provides four pushbutton switches. Each of these switches is debounced using a
Schmitt Trigger circuit, as indicated in Figure 5.3. The four outputs called KEY0, KEY1, KEY2, and
KEY3 of the Schmitt Trigger devices are connected directly to the Cyclone II FPGA. Each switch
provides a high logic level (3.3 volts) when it is not pressed, and provides a low logic level (0 volts)
when depressed. Since the pushbutton switches are debounced, they are appropriate for use as clock
or reset inputs in a circuit.
PROG RUN /
MAX
3128
"PROG"
EPCS16
Serial
Configuration
Device
Figure 5.2. The AS configuration scheme.
Figure 5.3. Switch debouncing.
AS Mode
Config
Auto
Power-on Config
32
DE2-70 User Manual
JTAG Config Port