Configuring Cyclone II Devices
device releases its nSTATUSpin after a reset time-out period (maximum
of 40 µs). When the nSTATUSpin is released and pulled high by a pull-up
resistor, the configuration device reconfigures the chain. If this option is
turned off, the external system must monitor nSTATUSfor errors and
then pulse nCONFIGlow for at least 2 µs to restart configuration. The
external system can pulse the nCONFIGpin if the pin is under system
control rather than tied to VCC
.
Additionally, if the configuration device sends all of its data and then
detects that the CONF_DONEpin has not transitioned high, it recognizes
that the FPGA has not configured successfully. Enhanced configuration
devices wait for 64 DCLKcycles after the last configuration bit was sent for
the CONF_DONEpin to transition high. EPC2 devices wait for 16 DCLK
cycles. After that, the configuration device pulls its OE pin low, which in
turn drives the target device’s nSTATUSpin low. If you turn on the Auto-
restart configuration after error option in the Quartus II software, the
target device resets and then releases its nSTATUSpin after a reset time-
out period (maximum of 40 µs). When nSTATUStransitions high again,
the configuration device reconfigures the FPGA.
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 PS Configuration Using a Configuration Device
You can use Altera enhanced configuration devices (EPC16, EPC8, and
EPC4 devices) or EPC2 and EPC1 configuration devices to configure
multiple Cyclone II devices in a PS configuration chain.
Figure 13–14 shows how to configure multiple devices with an enhanced
configuration device. This circuit is similar to the configuration device
circuit for a single device, except Cyclone II devices are cascaded for
multiple device configuration.
Altera Corporation
February 2007
13–37
Cyclone II Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
