Answers Database
Virtex Configuration: How can the users enable the Pullups in the IOs during Virtex Configuration.
Record #7333
Product Family: Hardware
Product Line: Virtex
Product Part: Virtex General Hardware
Problem Title:
Virtex Configuration: How can the users enable the Pullups in the IOs during Virtex
Configuration.
Problem Description:
Urgency: standard
Problem Description:
Virtex has eight configuration modes. Besides Master Serial, Slave Serial, Select MAP
and Boundary Scan, it also has Master Serial with Pullups, Slave Serial with Pullups,
Select MAP with Pullups, and Boundary Scan with Pullups.
How can one enable the Pullups? Where are the Pullups from?
Solution 1:
Virtex IOs are in Tri-states during configuration. However, users can still enable the
Pullups in the IOs by changing the mode pin settings. The pullups follow the mode pins
in an asynchronous manner. If the device enters the configuration sequence (by pulling
PROG low or cycling power), the pullups will be immediately enabled as appropriate.
Virtex can be configured in the following modes with the IOs being pulled up:
Master Serial, Slave Serial, Select MAP, and Boundary Scan(JTAG).
The Pullups are the internal Pullups in the IO blocks. The activation of the
Pullup resistor prior to configuration is controlled on a global basis by the mode pins.
For instance, if the mode pins are set to 011, this would automatically enable
the internal pullups in the IOs for the device to be configured in the Slave Serial mode.
For detailed information on Virtex configuration, please see (Xilinx XAPP138).
End of Record #7333 - Last Modified: 01/27/00 17:20 |
