Atmel AT85DVK-07 Spezifikationen PDF herunterladen (Seite 177)

177

AT85C51SND3Bx

7632A–MP3–03/06

Table 195. Spare Zone Content

The bytes which are not managed by the NFC are written to FFh.

Write Session The spare zone is processed after the ‘data zone’.

The NFC will initialize the byte at offset 3 with the byte contained in the NFUDAT regis-

ter, and the ‘Logical Block Address’ (offsets 6-7, also duplicated at offsets 11-12) with

the 2-bytes-descriptor stored in NFLOG (see

Table 197, page 179 for more details).

Then the ECC is written at position 13, 14 and 15 for the ECC group 1 (from data byte 0

to data byte 255), and at position 8, 9 and 10 for ECC group 2 (from data byte 256 to

data byte 511).

The ECC used can detects 2 wrong bits or more, and correct one bit.

Read Session The NFC does only check (depending configuration explained in the next chapter) the

ECC (ECC-1 and ECC-2).

Spare Zone Management The way the spare zone is handled depends on 3 bits: the SPZEN bit in NFCON which

is the automatic management enable bit, the ECCEN which is the ECC management

enable bit and the ECCRDYE bit which is the ECC ready interrupt enable bit.

Table 196

summarizes the spare zone behavior according to those control bits. Following section

give detail on the management modes.

Table 196. Spare Zone Management Modes

Offset Description

0-1 User Data Area. Shall be managed by software.

2 ECC Valid. Managed by NFC.

3 User Data Byte. Managed by NFC through NFUDAT register.

4 Data Status Flag. Shall be managed by software.

5 Block Status Flag. Shall be managed by software.

6-7

Logical Block Address. Managed by NFC through NFLOG register (see Section “Logical

Block Address”).

8-10 ECC Area-2. Managed by NFC.

11-12

Logical Block Address. Managed by NFC through NFLOG register (see Section “Logical

Block Address”).

13-15 ECC Area-1. Managed by NFC.

SPZEN ECCEN ECCRDYE Description

0 0 X

Spare Zone Management Mode 1

The spare zone is not managed by the NFC.

1 1 0

Spare Zone Management Mode 2

The spare zone is entirely managed by the NFC.

X 1 1

Spare Zone Management Mode 3

The spare zone is not automatically managed by the NFC. However,

an interrupt is triggered when the ECC FIFO is full, so after each 512

bytes processed. The user must program/verify the spare zone.

1 2 ... 172 173 174 175 176 177 178 179 180 181 182 ... 262 263

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