Altera Cyclone IV Device Handbook page 232

8–68
Table 8–21
configuration pins in the Quartus II software, they are available as general-purpose
user I/O pins. Therefore, during configuration, these pins function as user I/O pins
and are tri-stated with weak pull-up resistors.
Table 8–21. Optional Configuration Pins
Pin Name User Mode
N/A if option is on.
CLKUSR
I/O if option is off.
N/A if option is on.
INIT_DONE
I/O if option is off.
N/A if option is on.
DEV_OE
I/O if option is off.
N/A if option is on.
DEV_CLRn
I/O if option is off.
Cyclone IV Device Handbook,
Volume 1
Chapter 8: Configuration and Remote System Upgrades in Cyclone IV Devices
lists the optional configuration pins. If you do not enable these optional
Pin Type
Optional user-supplied clock input synchronizes the
initialization of one or more devices. This pin is enabled by
turning on the Enable user-supplied start-up clock (CLKUSR)
option in the Quartus II software.
Input
In AS configuration for Cyclone IV GX devices, you can use this
pin as an external clock source to generate the DCLK by
changing the clock source option in the Quartus II software in
the Configuration tab of the Device and Pin Options dialog
box.
Status pin is used to indicate when the device has initialized and
is in user-mode. When nCONFIG is low, the INIT_DONE pin is
tri-stated and pulled high due to an external 10-k pull-up
resistor during the beginning of configuration. After the option
bit to enable INIT_DONE is programmed into the device (during
the first frame of configuration data), the INIT_DONE pin goes
low. When initialization is complete, the INIT_DONE pin is
released and pulled high and the device enters user mode.
Thus, the monitoring circuitry must be able to detect a low-to-
Output
high transition. This pin is enabled by turning on the Enable
open-drain
INIT_DONE output option in the Quartus II software.
The functionality of this pin changes if the Enable OCT_DONE
option is enabled in the Quartus II software. This option
controls whether the INIT_DONE signal is gated by the
OCT_DONE signal, which indicates the power-up on-chip
termination (OCT) calibration is complete. If this option is
turned off, the INIT_DONE signal is not gated by the OCT_DONE
signal.
Optional pin that allows you to override all tri-states on the
device. When this pin is driven low, all I/O pins are tri-stated;
when this pin is driven high, all I/O pins behave as
Input
programmed. This pin is enabled by turning on the Enable
device-wide output enable (DEV_OE) option in the Quartus II
software.
Optional pin that allows you to override all clears on all device
registers. When this pin is driven low, all registers are cleared;
when this pin is driven high, all registers behave as
Input
programmed. You can enable this pin by turning on the Enable
device-wide reset (DEV_CLRn) option in the Quartus II
software.
Configuration
Description
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