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AR# 2548

FPGA Configuration: EXPRESS MODE Does Not Work in XC4000EX/XL/XLT FAMILIES.

Description

keywords: Express mode, Configuration, 4000ex, 4000xl

General Description:

Express mode configuration in these devices will result in

incorrect behavior even though the configuration sequence is

successful (DONE goes HIGH and INIT does not go LOW) and

readback for the bitstream is succesful. However, the logic

values on the device may not be correct. Also, users may notice

unusually high power consumption even when there are no

signals switching inside these parts.

Solution

Express Mode is Fully functional and Supported for the

XC4000XLA, SpartanXL, and XC5200 Families.

Users of XC4000EX/XL should be guided to alternative

configuration modes. The closest to Express mode is the

Synchronous Peripheral mode. Changes on the mode pins and a

configuration clock with different characteristics are required

to migrate to peripheral synchronous mode.

One important difference is that in express mode it takes 1

cclock cycle to clock a configuration byte while in peripheral

mode it takes 8 cclock cycles.

For more details refer to Configuration Section in the

Programmable Data Book.

AR# 2548
Date Created 08/21/2007
Last Updated 05/07/2014
Status Archive
Type General Article