SAA2501 Datasheet, PDF (26/52 Pages) NXP Semiconductors – Digital Audio Broadcast DAB decoder

Philips Semiconductors
Digital Audio Broadcast (DAB) decoder
Preliminary specification
SAA2501
Table 19 Validity of SAA2501 readable data items with respect to the decoding subprocess (notes 1 and 2)
SAA2501 IS DECODING FRAME n
SAA2501 IS DECODING FRAME n + 1
DST2 = 0; SUBPROCESS
DST2 = 1; SUBPROCESS
0
not valid
−
−
1
2
3
0
Ancillary Data item (frame n − 1)
frame header items (frame n)
not valid
not valid
error report: BALOK (frame n)
not valid
error report: DECFM
(frame n)
1
−
−
not valid
2
−
−
−
not valid
3
−
−
−
−
Notes
1. The Table shows following:
a) The received Ancillary Data that was multiplexed in frame n−1 becomes valid after subprocess 0 of frame n, and
may be read during subprocesses 1, 2 and 3 of frame n.
b) The decoded and used frame headers for frame n become valid after subprocess 0 of frame n, and may be read
during subprocesses 1, 2 and 3 of frame n.
c) Flag BALOK for frame n in the error report item becomes valid after subprocess 1 of frame n, and may be read
during subprocesses 2 and 3 of frame n and subprocess 0 of frame n+1.
d) Flag DECFM for frame n in the error report item becomes valid after subprocess 2 of frame n, and may be read
during subprocesses 3 of frame n and 0 of frame n+1.
2. Note that during subprocess 3 all data items can be read.
7.20.6 DATA ITEMS
Data can be transferred to or from the SAA2501 in data
items. This section describes the general protocol to
accomplish item data transfer, followed by the individual
SAA2501 data items. Optional enhancements on the
general protocol are described in Chapter 8 Section 8.2.
7.20.6.1 General data items
The data items of the SAA2501 are transferred (i.e. read
or written, depending on whether the data item is of
readable or writeable type) in bytes. A data item transfer is
initiated by writing the corresponding type I control byte
(see Section 7.20.4) to the SAA2501. The transfer of every
subsequent item data byte must be preceded by reading
the status until status flag L3RDY (see Section 7.20.5) is
HIGH.
L3RDY may be tested alternatively by polling L3DATA,
avoiding the need to transfer the whole status byte. Status
polling is not required while transferring the APU
coefficients item. Table 20 shows an example of how
bytes ‘DDDDDDDD’ of a 2 byte data item, with the
corresponding control byte ‘CCCCCCCC’, can be read.
The writing of item data bytes occurs in a similar way.
January 1995
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