Xilinx MicroBlaze Spartan-3E 1600E Edition User Manual page 10

Chapter 2: Switches, Buttons, and Knob
Operation
Each LED has one side connected to ground and the other side connected to a pin on the
Spartan-3E device via a 390Ω current limiting resistor. To light an individual LED, drive
the associated FPGA control signal High.
UCF Location Constraints
Figure 2-11
I/O pin assignment, the I/O standard used, the output slew rate, and the output drive
current.
Related Resources
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Spartan-3E
Development Board
Figure 2-10: Eight Discrete LEDs
provides the UCF constraints for the four push-button switches, including the
NET "LED<7>" LOC = "A8" | IOSTANDARD = LVTTL | SLEW = SLOW | DRIVE = 8 ;
NET "LED<6>" LOC = "G9" | IOSTANDARD = LVTTL | SLEW = SLOW | DRIVE = 8 ;
NET "LED<5>" LOC = "A7" | IOSTANDARD = LVTTL | SLEW = SLOW | DRIVE = 8 ;
NET "LED<4>" LOC = "D13" | IOSTANDARD = LVTTL | SLEW = SLOW | DRIVE = 8 ;
NET "LED<3>" LOC = "E6" | IOSTANDARD = LVTTL | SLEW = SLOW | DRIVE = 8 ;
NET "LED<2>" LOC = "D6" | IOSTANDARD = LVTTL | SLEW = SLOW | DRIVE = 8 ;
NET "LED<1>" LOC = "C3" | IOSTANDARD = LVTTL | SLEW = SLOW | DRIVE = 8 ;
NET "LED<0>" LOC = "D4" | IOSTANDARD = SSTL2_I ;
Figure 2-11: UCF Constraints for Eight Discrete LEDs
Rotary Encoder Interface for Spartan-3E Starter Kit (Reference Design)
http://www.xilinx.com/s3estarter
http://www.xilinx.com/sp3e1600E
MicroBlaze Development Kit Spartan-3E 1600 Edition User Guide
UG257_02_10_061306
UG257_02_11_062106
UG257 (v1.1) December 5, 2007
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