描述

Does the PROGRAM pin on a Virtex device have a programmable pull-up? Is this pull-up active prior to configuration?

解决方案

Virtex, Virtex-E, Virtex-II, and Spartan-II devices all have programmable pull-ups on the PROGRAM pins.  

Prior to configuration (before the DONE pin goes high), the pull-up is always enabled on the PROGRAM pin, regardless of the configuration mode. Note that the pull-up on the PROGRAM pin is completely unrelated to the "pre-configuration IOB pull-up" modes. For more information on pre-configuration IOB pull-ups, please refer to the configuration section of the applicable data sheet or user guide. Data sheets are located at: 

http://www.xilinx.com/support/documentation/index.htm
 

After configuration (after the DONE pin goes High), the pull-up on the PROGRAM pin is activated with this BitGen setting: 

-g ProgPin:PullUp 

To disable this pull-up in BitGen, set this parameter to "PullNone": 

-g ProgPin:PullNone