AR# 5429

12.1 Constraints - Prohibiting multi-purpose configuration pins

Description

To simplify my board design, I want to prohibit multi-purpose configuration pins.

What are these pins, and how are they prohibited?

Solution

Several special purpose pins are available for user I/O after configuration. The majority of these pins require a direct instantiation in order to be used (for example, TDO, MD1, etc.). Specific primitives must be assigned to utilize these pins, and they cannot be prohibited or pin-locked.

However, PAR uses a number of special purpose pins, and these pins can be prohibited by adding the following to the UCF:
CONFIG PROHIBIT = P34;

Special purpose pins are dependent upon package, not family. You can find out more about special purpose pins for a specific device in the appropriate device data sheet.

AR# 5429
Date 12/15/2012
Status Active
Type General Article