11–2
Altera Corporation
Stratix Device Handbook, Volume 2
July 2005
Device Configuration Overview
■
The Remote System Configuration with Stratix & Stratix GX Devices
chapter
f
For more information on setting device configuration options or
generating configuration files, see the Software Setting chapter in
Volume 2 of the Configuration Handbook.
Device
Configuration
Overview
During device operation, the FPGA stores configuration data in SRAM
cells. Because SRAM memory is volatile, you must load the SRAM cells
with the configuration data each time the device powers up. After
configuration, the device must initialize its registers and I/O pins. After
initialization, the device enters user mode.
Figure 11–1 shows the state of
the device during the configuration, initialization, and user mode.
Figure 11–1. Stratix & Stratix GX Configuration Cycle
(1)
During initial power up and configuration, CONF_DONE is low. After configuration, CONF_DONE goes high. If the
device is reconfigured, CONF_DONE goes low after nCONFIG is driven low.
(2)
User I/O pins are tri-stated during configuration. Stratix and Stratix GX devices also have a weak pull-up resistor
on I/O pins during configuration that are enabled by nIO_PULLUP. After initialization, the user I/O pins perform
the function assigned in the user’s design.
(3)
If the INIT_DONE pin is used, it will be high because of an external 10 k
Ω resistor pull-up 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 will go low.
(4)
DCLK
should not be left floating. It should be driven high or low.
(5)
DATA0
should not be left floating. It should be driven high or low.
You can load the configuration data for the Stratix or Stratix GX device
using a passive configuration scheme. When using any passive
configuration scheme, the Stratix or Stratix GX device is incorporated into
a system with an intelligent host, such as a microprocessor, that controls
the configuration process. The host supplies configuration data from a
storage device (e.g., a hard disk, RAM, or other system memory). When
using passive configuration, you can change the target device’s
High-Z
nCONFIG
nSTATUS
CONF_DONE (1)
DCLK
DATA
User I/O Pins (2)
INIT_DONE (3)
MODE
High-Z
D0
D1
D2
D3
D(N – 1)
DN
Configuration
Initialization
User
High-Z
User I/O
Configuration
(4)
(5)