參數(shù)資料
型號： SAA2502H
廠商： NXP SEMICONDUCTORS
元件分類： 消費家電
英文描述： ISO/MPEG Audio Source Decoder
中文描述： SPECIALTY CONSUMER CIRCUIT, PQFP44
封裝： PLASTIC, SOT-307, QFP-44
文件頁數(shù)： 49/64頁
文件大?。?/td> 318K
代理商： SAA2502H
1997 Nov 17
49
Philips Semiconductors
Preliminary specification
ISO/MPEG Audio Source Decoder
SAA2502
8.1.4.2
Ancillary data containing scale factor CRCs
If scale factor CRC protection is enabled, the required CRC values for each audio frame are carried among the ancillary
data of the previous frame. This approach ensures MPEG compatibility for encoded streams with scale factor protection.
The SAA2502 assumes the next ancillary data format when scale factor CRC protection is enabled:
The last 2 bytes of each audio frame carry the minimum ancillary data. These two bytes are called FPAD (fixed
program associated data) bytes. Definition of the content of FPAD is up to the application but should contain
information on the length of the remainder of the ancillary data if that length is variable. FPAD bytes are stored to be
read by the microcontroller.
The byte before the FPAD bytes is called CRC0 and contains the scale factor CRC for sub-bands 0 to 3.
The byte before CRC0 is called CRC1 and contains the scale factor CRC for sub-bands 4 to 7.
An optional byte CRC2 may precede CRC1. It contains the scale factor CRC for sub-bands 8 to 15 and is present only
for sub-band limits greater than 8.
There may be an optional byte CRC3 before CRC2. It contains the scale factor CRC for sub-bands 16 to 31 and will
be present only for sub-band limits greater than 16.
Before the sub-band CRCs more ancillary data may be present. This extra ancillary data is called XPAD (extended
program associated data). If XPAD is present it will be stored to be read by the microcontroller (up to a maximum of
52 bytes).
8.1.4.3
Boundary scan test provision
The SAA2502 contains a 5-pin interface for Boundary Scan Test (BST):
Table 57
Boundary scan test
In normal use TRST must be LOW, TCK must be LOW or HIGH while TDI and TMS must be HIGH or not connected.
Otherwise when any of these pins is used in a way not designed correctly for boundary scan test purposes in the
application, damaging of the SAA2502 and/or the components surrounding it may occur.
SIGNAL
DIRECTION
FUNCTION
TDI
TDO
TMS
TCK
TRST
input
output
input
input
input
boundary scan test data input
boundary scan test data output
boundary scan test mode select
boundary scan test clock
boundary scan test reset
Fig.27 Ancillary data containing scale factor CRCs.
handbook, full pagewidth
MGE486
XPAD
52
FPAD
2
FPAD
1
XPAD
1
CRC
3
CRC
2
CRC
1
CRC
0
- - -
optional
optional
optional
optional
optional
end of frame n
start of frame n
+
1
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相關(guān)代理商/技術(shù)參數(shù)
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SAA2505H-M1 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Digital multi-channel audio IC DUET
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