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M64403FP

ERROR CORRECTION WITH VARIABLE LENGTH AND DISTANCE

MITSUBISHI ELECTRIC  

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MITSUBISHI ICs (LSI)

M64403FP

ERROR CORRECTION WITH VARIABLE LENGTH AND DISTANCE

DECODE MODE SETTING METHOD

Decode mode is able to set at IRDY=H. Decode mode table is as

follows. Decode mode should be changed after all operations that

are set before changing.

Decode mode table

MOD0

0

1

0

1

0

1

0

1

MOD1

0

0

1

1

0

0

1

1

MOD2

0

0

0

0

1

1

1

1

mode

code (0) error correction

code (1) error correction

code (2) error correction

code (3) error correction

code (0) erasure correction

code (1) erasure correction

code (2) erasure correction

code (3) erasure correction

CODE WORD INPUT METHOD

Code word is able to input at IRDY=H. IRDY changes H to L when

head symbol for code word is input. And IRDY changes L to H

when the last symbol of code word is input.

DHEF should be H and DIEN should be L when the head symbol

of code word is input. DIEN is input enable signal for code word

and while it's L, input data is recognized as valid data and latched

to the internal circuit at rising edge of CLKI.

If the syndrome calculation for the 2nd code word finishes while the

1st code word is executed at Euclidean calculation stage, the

syndrome data that is latched internally is overwritten (called

syndrome collision) and the correcting operation for the 1st code

word is impossible. In this case, SYCR changes to H and informs

external of its status. (If the last symbol of code word is input at

SBFB=H, decoding is operated safely.)

SYCR which changes to H is reset by system reset (REST=L).

ERASURE FLAG INPUT METHOD AND

ERASURE CORRECTION MODE

Erasure correcting mode is set by the setting of erasure threshold

to address 8 to B for parameter register and the setting of

MOD2=H for decode mode signal. Erasure flag (EREN) should

input H by synchronization with symbol data of code word.

Follows are about erasure threshold.

(1) Constrained error correction mode is derived when the bit0 (D0)

of the parameter register address-E is set to L.

If the input erasure count is over the erasure threshold value(∗3),

the operation is adopted ordinary error correction mode by

force.

(2) Erasure correction priority mode is derived when the bit0 (D0)

of the parameter register address-E is set to H.

If the error is detected at syndrome calculation and erasure

count is over the erasure threshold value(∗4,) M64403FP regards

its operation as uncorrectable and correcting operation doesn't

execute.

In any cases ((∗3),(∗4)), EROV (erasure over flag) changes to H.

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