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applications that require the device to operate error-free may require that your designs account for these
errors.
You can enable the error detection circuitry to detect soft errors. Each data frame stored in the CRAM
contains a 32-bit precomputed CRC value. When this feature is enabled, the error detection circuitry
continuously computes a 32-bit CRC value for each frame in the CRAM and compares the CRC value against
the precomputed value.
• If the CRC values match, the 32-bit CRC signature in the
syndrome
register is set to zero to indicate that
no error is detected.
• Otherwise, the resulting 32-bit CRC signature in the
syndrome
register is non-zero to indicate a CRC
error. The
CRC_ERROR
pin is pulled high, and the error type and location are identified.
Within a frame, the error detection circuitry can detect all single-, double-, triple-, quadruple-, and quintuple-
bit errors. When a single-bit or double-adjacent error is detected, the error detection circuitry reports the
bit location and determines the error type for single-bit and double-adjacent errors. The probability of other
error patterns is very low and the reporting of bit location is not guaranteed. The probability of more than
five CRAM bits being flipped by soft errors is very low. In general, the probability of detection for all error
patterns is 99.9999%. The process of error detection continues until the device is reset by setting the
nCONFIG
signal low.
Specifications
This section lists the EMR update interval, error detection frequencies, and CRC calculation time for error
detection in user mode.
Minimum EMR Update Interval
The interval between each update of the error message register depends on the device and the frequency of
the error detection clock. Using a lower clock frequency increases the interval time, hence increasing the
time required to recover from a single event upset (SEU).
Table 8-1: Estimated Minimum EMR Update Interval in Cyclone V Devices
Timing Interval (µs)
Member Code
Variant
1.47
A2
Cyclone E
1.47
A4
1.79
A5
2.33
A7
3.23
A9
1.09
C3
Cyclone V GX
1.79
C4
1.79
C5
2.33
C7
3.23
C9
SEU Mitigation for Cyclone V Devices
Altera Corporation
CV-52008
Specifications
8-2
2013.11.12