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Xilinx CPLD Libraries Guide

Xilinx CPLD Libraries Guide

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About Design Elements<br />

This counter is asynchronously cleared, outputs Low, when power is applied. .For <strong>CPLD</strong> devices, you can<br />

simulate power-on by applying a High-level pulse on the PRLD global net.<br />

Logic Table<br />

Inputs Outputs<br />

CLR L CEU CED C Dz–D0 Qz–Q0 TCU TCD CEOU CEOD<br />

1 X X X X X 0 0 1 0 CEOD<br />

0 1 X X › Dn Dn TCU TCD CEOU CEOD<br />

0 1 X X fl Dn Dn TCU TCD CEOU CEOD<br />

0 0 0 0 X X No<br />

Change<br />

No<br />

Change<br />

No<br />

Change<br />

0 0<br />

0 0 1 0 › X Inc TCU TCD CEOU 0<br />

0 0 1 0 fl X Inc TCU TCD CEOU 0<br />

0 0 0 1 › X Dec TCU TCD 0 CEOD<br />

0 0 0 1 fl X Dec TCU TCD 0 CEOD<br />

0 0 1 1 › X Inc TCU TCD Invalid Invalid<br />

0 0 1 1 fl X Inc TCU TCD Invalid Invalid<br />

z = bit width - 1<br />

TCU = Qz•Q(z-1)•Q(z-2)•...•Q0<br />

TCD = Qz•Q(z-1)•Q(z-2)•...•Q0<br />

CEOU = TCU•CEU<br />

CEOD = TCD•CED<br />

Design Entry Method<br />

This design element is only for use in schematics.<br />

For More Information<br />

• See the appropriate <strong>CPLD</strong> User <strong>Guide</strong>.<br />

• See the appropriate <strong>CPLD</strong> Data Sheets.<br />

<strong>CPLD</strong> <strong>Libraries</strong> <strong>Guide</strong><br />

ISE 10.1 www.xilinx.com 179

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