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AR# 5666

Virtex Configuration - Configuring multiple Virtex devices in SelectMAP mode

Description

How can you configure multiple Virtex devices in SelectMAP mode and have all Virtex devices become active at the same time?

Solution

Connect the CCLK, Data, /WRITE, BUSY, DONE, and /INIT pins in parallel. Each Virtex device is loaded separately by asserting the /CS pin of each device.

The Host processor should follow these steps:

- Set /WRITE LOW.

- Sequence A:

1. Set /CS of one Virtex device LOW.

2. Send configuration Data.

3. At the end of the bitstream, deselect the Virtex device by setting its /CS pin HIGH.

4. Repeat Sequence A for all other Virtex devices.

- Disable Data Source.

- Configuration Completed - Done will go HIGH when all devices have released it.

The programming sequence for SelectMAP can be found in Flowchart form in the Virtex data sheet V2.5, (Figure 17, Page 2-17).

The "Virtex 2.5V FPGA Complete Data Sheet (all four Modules)" can be downloaded at:

http://www.xilinx.com/support/documentation/data_sheets/ds003.pdf

It is possible to configure multiple Virtex devices using SelectMAP without external circuitry, given the following conditions:

- The SelectMAP pins must not be persisted (-g Persist:No).

- The devices will NOT start up at the same time (i.e., the DONE pins should not be tied together).

- An extra I/O pin is available.

In the design of each device, an I/O needs to be added that is permanently tied to ground. This I/O should be routed on the board to the /CS pin of the next Virtex device in the SelectMAP chain. All the devices must have preconfiguration pull-ups enabled (010). When the first device starts up, it will drive the /CS line of the next device Low, effectively readying it for configuration.

This method could be very useful when using an 18V00 PROM or PROMs, or a similar method of sending the data stream in a constant fashion.

AR# 5666
Date Created 08/21/2007
Last Updated 12/15/2012
Status Active
Type General Article