Active Serial Configuration (Serial Configuration Devices)
f
For more information on configuration issues, see the Debugging
Configuration Problems chapter of the Configuration Handbook and the
FPGA Configuration Troubleshooter on the Altera web site
(www.altera.com).
Multiple Device AS Configuration
You can configure multiple Cyclone II devices using a single serial
configuration device. You can cascade multiple Cyclone II devices using
the chip-enable (nCE) and chip-enable-out (nCEO) pins. Connect the nCE
pin of the first device in the chain to ground and connect the nCEOpin to
the nCEpin of the next device in the chain. Use an external 10-kΩpull-up
resistor to pull the nCEOsignal high to its VCCIO level to help the internal
weak pull-up resistor. When the first device captures all of its
configuration data from the bitstream, it transitions its nCEOpin low,
initiating the configuration of the next device in the chain. You can leave
the nCEOpin of the last device unconnected or use it as a user I/O pin
after configuration if the last device in chain is a Cyclone II device.
1
The Quartus II software sets the Cyclone II device nCEOpin as
an output pin driving to ground by default. If the device is in a
chain, and the nCEOpin is connected to the next device’s nCE
pin, you must make sure that the nCEOpin is not used as a user
I/O pin after configuration. The software setting is in the
Dual-Purpose Pins tab of the Device & Pin Options dialog box
in Quartus II software.
The first Cyclone II device in the chain is the configuration master and
controls the configuration of the entire chain. Select the AS configuration
scheme for the first Cyclone II device and the PS configuration scheme for
the remaining Cyclone II devices (configuration slaves). Any other
Altera® device that supports PS configuration can also be part of the chain
as a configuration slave. In a multiple device chain, the nCONFIG,
nSTATUS, CONF_DONE, DCLK, and DATA0pins of each device in the chain
are connected (see Figure 13–4). Figure 13–4 shows the pin connections
for this setup.
13–12
Cyclone II Device Handbook, Volume 1
Altera Corporation
February 2007
ALTERA [ ALTERA CORPORATION ]
