EP3C16F256I7 Altera, EP3C16F256I7 Datasheet - Page 273

• Manufacturer Part Number: EP3C16F256I7
• Description: Cyclone III
• Manufacturer: Altera

Altera Corporation-Preliminary
March 2007
need to send additional clock cycles from an external source to the
CLKUSR pin during the initialization stage. Additionally, you can use the
CLKUSR pin as a user I/O pin.
You also have the flexibility to synchronize initialization of multiple
devices or to delay initialization with the CLKUSR option. Using the
CLKUSR pin allows you to control when your device enters user mode.
The device can be delayed from entering user mode for an indefinite
amount of time. The Enable user-supplied start-up clock (CLKUSR)
option can be turned on in the Quartus II software from the General tab
of the Device & Pin Options dialog box. When you click Enable user-
supplied start-up clock (CLKUSR), the CLKUSR pin is the initialization
clock source. Supplying a clock on CLKUSR does not affect the
configuration process. After all configuration data has been accepted and
CONF_DONE goes high, Cyclone III devices require 3,180 clock cycles to
initialize properly and enter user mode. Cyclone III devices support a
CLKUSR fMAX of 133 MHz.
An optional INIT_DONE pin is available, which signals the end of
initialization and the start of user-mode with a low-to-high transition.
The Enable INIT_DONE Output option is available in the Quartus II
software from the General tab of the Device & Pin Options dialog box. If
the INIT_DONE pin is used, it will be high due to an external 10 KΩ
pull-up resistor when nCONFIG is low and during the beginning of
configuration. Once 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. This low-to-high transition
signals that 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.
If an error occurs during configuration, Cyclone III devices assert the
nSTATUS signal low, indicating a data frame error, and the CONF_DONE
signal stays low. 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 Cyclone III device resets the
configuration device by pulsing FLASH_nCE, releases nSTATUS after a
reset time-out period (maximum of 80 μs), and retries configuration. If
this option is turned off, the system must monitor nSTATUS for errors and
then pulse nCONFIG low for at least 500 ns to restart configuration.
When the Cyclone III device is in user mode, you can initiate
reconfiguration by pulling the nCONFIG pin low. The nCONFIG pin
should be low for at least 500 ns. When nCONFIG is pulled low, the
Cyclone III device is reset. The Cyclone III device also pulls nSTATUS and
Active Parallel Configuration (Supported Flash Memories)
Cyclone III Device Handbook, Volume 1
10–37