EP2S90F1020C5 Datasheet, PDF (558/768 Pages) Altera Corporation – Stratix II Device Handbook, Volume 1

Configuration Features
1 When using FPP mode, the intelligent host must provide a DCLK
that is 4× the data rate. Therefore, the configuration data must be
valid for four DCLK cycles.
The decompression feature supported by Stratix II and Stratix II GX
devices is different from the decompression feature in enhanced
configuration devices (EPC16, EPC8, and EPC4 devices), although they
both use the same compression algorithm. The data decompression
feature in the enhanced configuration devices allows them to store
compressed data and decompress the bitstream before transmitting it to
the target devices. When using Stratix II and Stratix II GX devices in FPP
mode with enhanced configuration devices, the decompression feature is
available only in the enhanced configuration device, not the Stratix II or
Stratix II GX device.
In PS mode, use the Stratix II or Stratix II GX decompression feature
because sending compressed configuration data reduces configuration
time. Do not use both the Stratix II or Stratix II GX device and the
enhanced configuration device decompression features simultaneously.
The compression algorithm is not intended to be recursive and could
expand the configuration file instead of compressing it further.
When you enable compression, the Quartus II software generates
configuration files with compressed configuration data. This compressed
file reduces the storage requirements in the configuration device or flash
memory, and decreases the time needed to transmit the bitstream to the
Stratix II or Stratix II GX device. The time required by a Stratix II or
Stratix II GX device to decompress a configuration file is less than the
time needed to transmit the configuration data to the device.
There are two ways to enable compression for Stratix II and Stratix II GX
bitstreams: before design compilation (in the Compiler Settings menu)
and after design compilation (in the Convert Programming Files
window).
To enable compression in the project’s compiler settings, select Device
under the Assignments menu to bring up the Settings window. After
selecting your Stratix II or Stratix II GX device, open the Device & Pin
Options window, and in the General settings tab enable the check box for
Generate compressed bitstreams (as shown in Figure 7–1).
7–6
Stratix II Device Handbook, Volume 2
Altera Corporation
January 2008