Altera Internal Memory (RAM and ROM) IP Core Bedienungsanleitung PDF herunterladen (Seite 25)

Error Correction Code

Error correction code (ECC) allows you to detect and correct data errors at the output of the memory.

The Stratix III and Stratix IV M144K memory blocks have built-in ECC support of up to x64-wide simple

dual-port mode while the Stratix V M20K memory blocks have built-in ECC support of x32-wide simple

dual-port mode. The ECC in Stratix III and IV can perform single-error-correction double-error

detection (SECDED), in which it can detect and fix a single-bit error or detect two-bit errors (without

fixing). The Stratix V ECC feature can perform single error correction, double adjacent error correction,

and triple adjacent error detection, in which it can detect and fix a single bit error event or a double

adjacent error event, or detect three adjacent errors without fixing the errors. However, the Stratix V ECC

feature cannot detect four or more errors.

The ECC feature is not supported in the following conditions:

• mixed-width port feature is used

• byte-enable feature is engaged

Note: The Mixed-port RDW for old data mode is not supported when the ECC feature is engaged. The

result for RDW is Don't Care.

The M144K ECC status is communicated via a three-bit status flag eccstatus[2..0]. while the M20K ECC

status is communicated with a two-bit ECC status flag eccstatus[1..0] where eccstatus[1] corresponds to

the signal e (error) and eccstatus[0] corresponds to the signal ue (uncorrectable error).

Status

M144K M20K

eccstatus[2..0]

eccstatus[1..0]

eccstatus[1] e eccstatus[0] ue

No error 000 0 0

Single error and fixed 011 — —

Double error and no fix 101 — —

Illegal

001 0 1

010 0 1

Illegal

100 0 1

11X 0 1

A correctable error occurred

and the error has been

corrected at the outputs;

however, the memory array

has not been updated.

— 1 0

An uncorrectable error

occurred and uncorrectable

data appears at the output.

— 1 1

UG-01068

2014.12.17

Error Correction Code

3-15

Embedded Memory Functional Description

Altera Corporation

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