9–16
Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family
Configuration Features
1
1
When connecting a serial configuration device to the Cyclone III device family in the
multi-device AS configuration, you must connect a 25- series resistor at the near end
of the serial configuration device for DATA[0]
.
In the multi-device AS configuration, the board trace length between the serial
configuration device to the master device of the Cyclone III device family must follow
the recommendations in Table 9–9 on page 9–20. You must also connect the repeater
buffers between the master and slave devices of the Cyclone III device family for
DATA[0]and DCLK. All I/O inputs must maintain a maximum AC voltage of 4.1 V. The
output resistance of the repeater buffers must fit the maximum overshoot equation
outlined in “Configuration and JTAG Pin I/O Requirements” on page 9–7.
As shown in Figure 9–4 on page 9–15, the nSTATUSand CONF_DONEpins on all target
devices are connected together with external pull-up resistors. These pins are
open-drain bidirectional pins on the devices. When the first device asserts nCEO(after
receiving all its configuration data), it releases its CONF_DONEpin. However, the
subsequent devices in the chain keep this shared CONF_DONEline low until they receive
their configuration data. When all target devices in the chain receive their
configuration data and release CONF_DONE, the pull-up resistor drives a high level on
this line and all devices simultaneously enter initialization mode.
1
Although you can cascade Cyclone III device family, serial configuration devices
cannot be cascaded or chained together.
If the configuration bitstream size exceeds the capacity of a serial configuration
device, you must select a larger configuration device, enable the compression feature,
or both. When configuring multiple devices, the size of the bitstream is the sum of the
individual devices configuration bitstreams.
Configuring Multiple Cyclone III Device Family with the Same Design
Certain designs require you to configure multiple Cyclone III device family with the
same design through a configuration bitstream or a .sof. You can do this using the
following methods:
■
Multiple SRAM Object Files
Single SRAM Object File
■
1
For both methods, the serial configuration devices cannot be cascaded or
chained together.
Multiple SRAM Object Files
Two copies of the .sof are stored in the serial configuration device. Use the first copy
to configure the master device of the Cyclone III device family and the second copy to
configure all the remaining slave devices concurrently. All slave devices must be of
the same density and package. The setup is similar to Figure 9–4 on page 9–15, in
which the master device is set up in AS mode and the slave devices are set up in PS
mode.
Cyclone III Device Handbook
Volume 1
August 2012 Altera Corporation
ALTERA [ ALTERA CORPORATION ]
