9–66
Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family
Configuration Features
Table 9–22 lists the dedicated configuration pins that must be connected properly on
your board for successful configuration. Some of these pins may not be required for
your configuration scheme.
Table 9–22. Dedicated Configuration Pins on Cyclone III Device Family (Part 1 of 4)
User
Mode
Configuration
Scheme
Pin Name
Pin Type
Description
4-bit configuration input that sets the Cyclone III device
family configuration scheme. These pins must be hardwired
to VCCA or GND. The MSEL[3..0]pins have internal 9-k
pull-down resistors that are always active.
MSEL [3..0]
N/A
N/A
All
All
Input
Some of the smaller devices or package options of
Cyclone III devices do not have the MSEL[3]pin; therefore,
the AP configuration scheme is not supported.
Configuration control input. Pulling this pin low with external
circuitry during user mode causes the Cyclone III device
family to lose its configuration data, enter a reset state, and
tri-state all I/O pins. Returning this pin to a logic-high level
starts a reconfiguration.
nCONFIG
Input
The Cyclone III device family drives nSTATUSlow
immediately after power-up and releases it after the POR
time.
■ Status output. If an error occurs during configuration,
nSTATUSis pulled low by the target device.
■ Status input. If an external source (for example, another
Cyclone III device family) drives the nSTATUSpin low
during configuration or initialization, the target device
enters an error state.
Bidirectional
open-drain
nSTATUS
N/A
All
Driving nSTATUSlow after configuration and initialization
does not affect the configured device. If you use a
configuration device, driving nSTATUSlow causes the
configuration device to attempt to configure the device, but
because the device ignores transitions on nSTATUSin user
mode, the device does not reconfigure. To start a
reconfiguration, nCONFIGmust be pulled low.
■ Status output. The target Cyclone III device family drives
the CONF_DONEpin low before and during configuration.
After all configuration data is received without error and
the initialization cycle starts, the target device releases
CONF_DONE.
Bidirectional ■ Status input. After all data is received and CONF_DONE
CONF_DONE
N/A
All
open-drain
goes high, the target device initializes and enters user
mode. The CONF_DONEpin must have an external 10-k
pull-up resistor in order for the device to initialize.
Driving CONF_DONElow after configuration and initialization
does not affect the configured device. Do not connect bus
holds or ADC to the CONF_DONEpin.
Cyclone III Device Handbook
Volume 1
August 2012 Altera Corporation
ALTERA [ ALTERA CORPORATION ]
