Configuring Cyclone II Devices
Table 13–12 describes the optional configuration pins. If these optional
configuration pins are not enabled 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 13–12. Optional Configuration Pins
Pin Name User Mode Pin Type
CLKUSR
Description
N/A if option is Input
on. I/O if option
is off.
This is an optional user-supplied clock input that
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
N/A if option is Output open-
on. I/O if option drain
is off.
This is a status pin that can be used to indicate when the
device has initialized and is in user mode. When nCONFIG
is low and during the beginning of configuration, the
INIT_DONEpin is tri-stated and pulled high due to an
external 10-kΩ pull-up resistor. Once the option bit to
enable INIT_DONEis programmed into the device (during
the first frame of configuration data), the INIT_DONEpin
goes low. When initialization is complete, the INIT_DONE
pin is released and pulled high and the FPGA 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.
INIT_DONE
N/A if option is Input
on. I/O if option
is off.
Optional pin that allows the user 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_OE
N/A if option is Input
on. I/O if option
is off.
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. This pin is enabled by turning on
the Enable device-wide reset (DEV_CLRn) option in the
Quartus II software.
DEV_CLRn
Altera Corporation
February 2007
13–69
Cyclone II Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
