at85c51snd3b ATMEL Corporation, at85c51snd3b Datasheet - Page 178

• Manufacturer Part Number: at85c51snd3b
• Description: Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

Write Session
Read Session
Spare Zone Management
178
AT85C51SND3B
Table 196. Spare Zone Content
The bytes which are not managed by the NFC are written to FFh.
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 198, page 180 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.
The NFC does only check (depending configuration explained in the next chapter) the
ECC (ECC-1 and ECC-2).
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 197
summarizes the spare zone behavior according to those control bits. Following section
give detail on the management modes.
Table 197. Spare Zone Management Modes
SPZEN
Offset
11-12
13-15
8-10
0
1
X
0-1
6-7
2
3
4
5
ECCEN
Description
User Data Area. Shall be managed by software.
ECC Valid. Managed by NFC.
User Data Byte. Managed by NFC through NFUDAT register.
Data Status Flag. Shall be managed by software.
Block Status Flag. Shall be managed by software.
Logical Block Address. Managed by NFC through NFLOG register (see Section “Logical
Block Address”).
ECC Area-2. Managed by NFC.
Logical Block Address. Managed by NFC through NFLOG register (see Section “Logical
Block Address”).
ECC Area-1. Managed by NFC.
0
1
1
ECCRDYE Description
X
0
1
Spare Zone Management Mode 1
The spare zone is not managed by the NFC.
Spare Zone Management Mode 2
The spare zone is entirely managed by the NFC.
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.
7632C–MP3–11/06