EP2S90F1020C5 Datasheet, PDF (612/768 Pages) Altera Corporation – Stratix II Device Handbook, Volume 1

Passive Serial Configuration
activates the configuration device because it sees its nCS pin drive low.
Once nCONFIG returns to a logic high level and nSTATUS is released by
the device, reconfiguration begins.
Figure 7–22 shows how to configure multiple devices with an enhanced
configuration device. This circuit is similar to the configuration device
circuit for a single device, except Stratix II or Stratix II GX devices are
cascaded for multi-device configuration.
Figure 7–22. Multi-Device PS Configuration Using an Enhanced Configuration Device
VCC (1)
VCC (1)
10 kΩ (3) 10 kΩ (3)
Stratix II or Stratix II GX
Device 2
MSEL3
DCLK
VCC
DATA0
MSEL2
nSTATUS
MSEL1 CONF_DONE
MSEL0
nCONFIG
N.C. nCEO
nCE
GND
VCC
GND
Stratix II or Stratix II GX
Device 1
MSEL3
DCLK
MSEL2
DATA0
nSTATUS
MSEL1 CONF_DONE
MSEL0
nCONFIG
nCEO
nCE
GND
Enhanced
Configuration
Device
DCLK
DATA
OE (3)
nCS (3)
nINIT_CONF (2)
Notes to Figure 7–22:
(1) The pull-up resistor should be connected to the same supply voltage as the configuration device.
(2) The nINIT_CONF pin is available on enhanced configuration devices and has an internal pull-up resistor that is
always active, meaning an external pull-up resistor should not be used on the nINIT_CONF-nCONFIG line. The
nINIT_CONF pin does not need to be connected if its functionality is not used. If nINIT_CONF is not used, nCONFIG
must be pulled to V_CC either directly or through a resistor.
(3) The enhanced configuration devices’ OE and nCS pins have internal programmable pull-up resistors. If internal
pull-up resistors are used, external pull-up resistors should not be used on these pins. The internal pull-up resistors
are used by default in the Quartus II software. To turn off the internal pull-up resistors, check the Disable nCS and
OE pull-ups on configuration device option when generating programming files.
f
1 Enhanced configuration devices cannot be cascaded.
When performing multi-device configuration, you must generate the
configuration device's POF from each project’s SOF. You can combine
multiple SOFs using the Convert Programming Files window in the
Quartus II software.
For more information on how to create configuration files for
multi-device configuration chains, refer to the Software Settings chapter
of the Configuration Handbook.
7–60
Stratix II Device Handbook, Volume 2
Altera Corporation
January 2008