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SET_DEFAULT_OVERRIDE

The SET_DEFAULT_OVERRIDE function is used to specify default values for the automatically-generated parts of XJTAG such as the Safe bitstream and Connection Test. These default overrides behave much like Constant Pins or Bus Disable Values, but only exist until the current XJEase runtime has exited. They will override any existing constant pin, disable or compliance values.

Syntax

SET_DEFAULT_OVERRIDE [ pinReference := I |
		       pinReference := INT value |
		       pinReference := DEFAULT_NONE ]
		     { , ... };

Parameters

pinReference

A STRING that identifies a pin in the netlist in the form 'board.component.pin'. This may be a string returned from the GET_PIN function. The board name is optional, but the reference must uniquely identify the pin; if there is any ambiguity with the device reference, then the board name must be supplied.

value

A boolean value where TRUE indicates that the pin should be driven high and FALSE that it should be driven low. The value I can be used to indicate that the pin should be not driven at all.

Errors

An error can occur in the following circumstances:

  • The device referenced by pinReference does not match any device in the project.
  • The pin referenced by pinReference does not exist on the device.
  • The pinReference supplied does not contain a board name and matches more than one device.

In both these cases, if the expressions are constant, the error will occur at compile-time. Otherwise, the error will occur at run-time, when the function is run.

Example

SET_DEFAULT_OVERRIDE "IC1.1" := 1,"IC1.2" := 1;
SET_DEFAULT_OVERRIDE "Board.IC1.3" := I;

Calling SET_DEFAULT_OVERRIDE again on the same pin will override any previous assignment.

SET_DEFAULT_OVERRIDE "IC1.1" := 1;
SET_DEFAULT_OVERRIDE "IC1.1" := 0;
//default value is now 0

Setting an override to a value will also write the value in the same manner as a SET statement. If the value cannot currently be driven a warning will be produced, such as:

Warning: Unable to drive default value of 0 for IC1.1 on net Net1.

Calling SET_DEFAULT_OVERRIDE on a pin with a value of DEFAULT_NONE will effectively remove any existing constant pin, disable or compliance values.

SET_DEFAULT_OVERRIDE "IC1.1" := DEFAULT_NONE;

Any changes made through SET_DEFAULT_OVERRIDE can be undone using the RESET_DEFAULT_OVERRIDE keyword.

See Also