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AR# 7660

XPLA2 - Reserving device configuration pins using the fitter


Keywords: XPLA, CoolRunner, XPLA2, fitter, configuration, pins, reserve, I/O

How do I tell the fitter not to assign XPLA2 device configuration pins to I/O signals?


Most of the pins used in configuration of the device can also be used as I/O; however, this complicates the design of the system or PCB. Therefore, most designers would rather not have the pins involved in the device configuration also assigned as I/O signals in the design.

To inform the fitter of the configuration mode used, you can specify a property either in the ABEL/PHDL source code (Xilinx Answer 7563) or in a control file (Xilinx Answer 7516).

Here is an example of the ABEL/PHDL property for the master serial configuration mode (please note the spacing):

xpla property 'config_master_serial';

The fitter will then assign only the pins involved in the specified configuration mode to I/O signals as a last resort; that is, there are no single-function I/O pins left.
AR# 7660
Date Created 08/21/2007
Last Updated 07/28/2009
Status Archive
Type General Article