AHA4011C-040 데이터 시트보기 (PDF) - Unspecified

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AHA4011C-040

10 MBytes/sec Reed-Solomon Error Correction Device

Unspecified 

Advanced Hardware Architectures, Inc.

2.6.1 INITIALIZATION REGISTERS

BYTE 1, ERASURE MULTIPLIER:

[7:0] Multiplier value that must be programmed

as shown in Appendix A. The table shows a

value to be programmed corresponding to

the block length selected.

BYTE 2, ERROR THRESHOLD:

[4:0] The threshold for determining

uncorrectability of a data block, and the

number of check bytes allocated for

correction only purposes. When not using

erasures, set to the same value as BYTE 3,

CHECK BYTES. Minimum value of 0x02

sets the Threshold to 2 and 0x14 sets to the

maximum, 20.

[6:5] Reserved. Set to 0.

[7] Not used. Don't care.

BYTE 3, CHECK BYTES:

[4:0] Number of check bytes in RS code, R.

Minimum setting of 0x02 indicates two

check bytes for R = 2 and 0x14 indicates the

maximum of 20.

[6:5] Reserved. Set to 0.

[7] Not used. Don't care.

BYTE 4, MESSAGE BYTES:

[7:0] Number of message bytes in code, K.

Minimum setting of 0x01 indicates 1 byte,

setting to 0xFD indicates the maximum 253

message bytes.

BYTE 5, BLOCK LENGTH:

[7:0] Number of bytes in block, N. Setting to

0x03 indicates 3 bytes, setting to 0xFF

indicates 255 bytes.

BYTE 6, CONTROL BYTE:

[0] RES

Reserved. Set to 0.

[1] NOPAR Parity Symbol Control

0

Check bytes are output

following the message bytes.

1

Check bytes are not output

following the message bytes.

Correction will be done

regardless depending upon the

bit 4, RAW, setting.

[2] CRCTS Correction Control

0

Outputs correction vectors; to

obtain corrected data,

externally XOR the correction

vector with the corresponding

message or check byte.

1

Outputs corrected data

[3] FOR

Forward Order Control

0

Outputs the block in reverse

order

1

Outputs the block in forward

order

[4] RAW

Raw Data

0

Outputs corrections or

corrected data per the CRCTS

bit

1

Outputs uncorrected, raw input

data or 0's depending upon the

CRCTS bit setting (See table

below). NOPAR bit and

CHECK BYTE register

settings are ignored.

[5] ERC

Erasure Rejection Control.

This bit is only used by the

device when the Erasures

exceed the ERROR

THRESHOLD or R settings.

This bit is ignored when the

Erasures are less than or equal

to ERROR THRESHOLD or

R.

0

If Erasures are greater than the

ERROR THRESHOLD or R

then erasures are discarded and

full correction is performed.

The block is flagged

uncorrectable and the output

CRTN will be high during the

last output byte of the block.

1

If Erasures are greater than

ERROR THRESHOLD or R

then erasures are discarded and

full correction is performed.

The output CRTN will be high

only when the block is

uncorrectable.

[7:6] Reserved, Set to 0.

RAW

0

0

1

1

CRCTS

Output

0

Correction vectors

1

Corrected data

0

Zero

1

Uncorrected raw input data

Page 6 of 24

PS4011C-0200

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