Datasheet
CoolRunner-II™ Starter Board Reference Manual 
Copyright Digilent, Inc. All rights reserved. 
Other product and company names mentioned may be trademarks of their respective owners. 
Page 3 of 4 
3  Clocks 
The CoolRunner-II board includes a fixed-frequency oscillator that 
produces an 8MHz clock signal. This primary oscillator output, 
labeled PCLK in the schematic, is connected to the GCLK2 pin of the 
CPLD (at P38) so that it can be routed to the internal clock divider. An 
unloaded socket for a standard half-size DIP oscillator is also 
provided at location IC3. 
4  User I/O 
The CoolRunner-II board provides two pushbuttons and two slide switches for inputs, and four red LEDs and a four-
digit LED display for outputs. 
The active-low pushbuttons and slide switches include series resistance for short-circuit protection. The LEDs are 
active low, and the seven-segment display uses decoupled-transistor active-high common anode signals and 
active-low cathodes. 
Three additional LEDs indicate USB power good (LD4), board power good (LD5), and USB link status (LD6). 
CoolRunner-II
38
Fixed Freq 
Oscillator
DSC1033
Oscillator 
Socket
32




