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