Istype Keyword

Syntax

signals [PIN | NODE] numbers ISTYPE 'attr';

signal A pin or node identifier.

number Optional pin or node numbers.

attr A string that specifies attributes for the signals, separated by commas.

Use

The ISTYPE statement defines attributes (characteristics) of signals (pins and nodes). You should use signal attributes to remove ambiguities in architecture-independent designs. Even when you have specified a device, using attributes ensures that the design operates consistently if the device is changed later.

You can combine a pin or node declaration with an ISTYPE statement in a single declaration. Supported attributes are listed below.

Example

F0, A pin istype 'invert, reg' ;

This declaration statement defines F0 and A as inverted D-type flip-flops. The following signal declarations are all supported:

q3,q2,q1,q0 NODE ISTYPE 'reg_SR';
Clk,a,b,c PIN 1,2,3,4;
reset PIN;
reset ISTYPE 'com';
Output PIN 15 ISTYPE 'reg,invert';

Istype Keywords for CPLD Designs