EP3C55F780I7 Datasheet, PDF (256/274 Pages) Altera Corporation – This section provides a complete overview of all features relating to the Cyclone III device family

11–4
Chapter 11: SEU Mitigation in the Cyclone III Device Family
Error Detection Block
Table 11–2 lists the CRC_ERROR pin.
Table 11–2. CRC_ERROR Pin Description
Device
Cyclone III
Cyclone III LS
CRC_ERROR
Pin Type
Description
Dedicated
Output or
Open Drain
Output
(Optional)
By default, the Quartus II software sets the CRC_ERROR pin as a dedicated output. If the
CRC_ERROR pin is used as a dedicated output, you must ensure that the V_CCIO of the bank in
which the pin resides meets the input voltage specification of the system receiving the signal.
Optionally, you can set this pin to be an open-drain output by enabling the option in the
Quartus II software from the Error Detection CRC tab of the Device and Pin Options dialog
box. Using the pin as an open-drain provides an advantage on the voltage leveling. To use this
pin as open-drain, you can tie this pin to V_CCIO of Bank 1 through a 10-k pull-resistor.
Alternatively, depending on the voltage input specification of the system receiving the signal,
you can tie the pull-up resistor to a different pull-up voltage.
Open Drain
Output
To use the CRC_ERROR pin, you can either tie this pin to V_CCIO through a 10-kpull-up
resistor, or depending on input voltage specification of the system receiving the signal, you
can tie this pin to a different pull-up voltage.
f For more information about the CRC_ERROR pin information for Cyclone III device
family, refer to the Cyclone III Pin-Out Files for Altera Devices page on the Altera^®
website.
1 WYSIWYG is an optimization technique that performs optimization on VQM (Verilog
Quartus Mapping) netlist in the Quartus II software.
Error Detection Block
Table 11–3 lists the types of CRC detection to check the configuration bits.
Table 11–3. Types of CRC Detection to Check the Configuration Bits
First Type of CRC Detection
■ CRAM error checking ability (32-bit CRC)
during user mode, for use by the
CRC_ERROR pin.
■ There is only one 32-bit CRC value, and
this value covers all the CRAM data.
Second Type of CRC Detection
■ 16-bit CRC embedded in every configuration data frame.
■ During configuration, after a frame of data is loaded into the device, the
pre-computed CRC is shifted into the CRC circuitry.
■ Simultaneously, the CRC value for the data frame shifted-in is calculated.
If the pre-computed CRC and calculated CRC values do not match,
nSTATUS is set low.
■ Every data frame has a 16-bit CRC. Therefore, there are many 16-bit CRC
values for the whole configuration bit stream.
■ Every device has a different length of configuration data frame.
This section focuses on the first type—the 32-bit CRC when the device is in user
mode.
Error Detection Registers
There are two sets of 32-bit registers in the error detection circuitry that store the
computed CRC signature and pre-calculated CRC value. A non-zero value on the
signature register causes the CRC_ERROR pin to set high.
Cyclone III Device Handbook
Volume 1
December 2011 Altera Corporation