EP2S90F1020C5 Datasheet, PDF (629/768 Pages) Altera Corporation – Stratix II Device Handbook, Volume 1

Configuring Stratix II and Stratix II GX Devices
INIT_DONE pin is released and pulled high. The microprocessor must be
able to detect this low-to-high transition that signals the device has
entered user mode. When initialization is complete, the device enters user
mode. In user-mode, the user I/O pins no longer have weak pull-up
resistors and function as assigned in your design.
To ensure DATA[7..0] is not left floating at the end of configuration, the
microprocessor must drive them either high or low, whichever is
convenient on your board. After configuration, the nCS, CS, nRS, nWS,
RDYnBSY, and DATA[7..0] pins can be used as user I/O pins. When
choosing the PPA scheme in the Quartus II software as a default, these
I/O pins are tri-stated in user mode and should be driven by the
microprocessor. To change this default option in the Quartus II software,
select the Dual-Purpose Pins tab of the Device & Pin Options dialog box.
If an error occurs during configuration, the device drives its nSTATUS pin
low, resetting itself internally. The low signal on the nSTATUS pin also
alerts the microprocessor that there is an error. If the Auto-restart
configuration after error option-available in the Quartus II software from
the General tab of the Device & Pin Options dialog box-is turned on, the
device releases nSTATUS after a reset time-out period (maximum of
100 µs). After nSTATUS is released and pulled high by a pull-up resistor,
the microprocessor can try to reconfigure the target device without
needing to pulse nCONFIG low. If this option is turned off, the
microprocessor must generate a low-to-high transition (with a low pulse
of at least 2 µs) on nCONFIG to restart the configuration process.
The microprocessor can also monitor the CONF_DONE and INIT_DONE
pins to ensure successful configuration. To detect errors and determine
when programming completes, monitor the CONF_DONE pin with the
microprocessor. If the microprocessor sends all configuration data but
CONF_DONE or INIT_DONE has not gone high, the microprocessor must
reconfigure the target device.
1
If you are using the optional CLKUSR pin and nCONFIG is pulled
low to restart configuration during device initialization, ensure
CLKUSR continues toggling during the time nSTATUS is low
(maximum of 100 µs).
When the device is in user-mode, a reconfiguration can be initiated by
transitioning the nCONFIG pin low-to-high. The nCONFIG pin should go
low for at least 2 µs. When nCONFIG is pulled low, the device also pulls
nSTATUS and CONF_DONE low and all I/O pins are tri-stated. Once
nCONFIG returns to a logic high level and nSTATUS is released by the
device, reconfiguration begins.
Altera Corporation
January 2008
7–77
Stratix II Device Handbook, Volume 2