8–68
Chapter 8: Configuration and Remote System Upgrades in Cyclone IV Devices
Configuration
May 2013
Altera Corporation
lists the optional configuration pins. If you do not enable these optional
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
Pin Type
Description
CLKUSR
N/A if option is on.
I/O if option is off.
Input
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.
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.
INIT_DONE
N/A if option is on.
I/O if option is off.
Output
open-drain
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-
high transition. This pin is enabled by turning on the
Enable
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.
DEV_OE
N/A if option is on.
I/O if option is off.
Input
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
programmed. This pin is enabled by turning on the
Enable
device-wide output enable (DEV_OE)
option in the Quartus II
software.
DEV_CLRn
N/A if option is on.
I/O if option is off.
Input
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
programmed. You can enable this pin by turning on the
Enable
device-wide reset (DEV_CLRn)
option in the Quartus II
software.
Summary of Contents for Cyclone IV
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