SAA2501 Datasheet, PDF (24/52 Pages) NXP Semiconductors – Digital Audio Broadcast DAB decoder

Philips Semiconductors
Digital Audio Broadcast (DAB) decoder
Preliminary specification
SAA2501
The actions shown in Fig.15 are:
1. In order for the SAA2501 to keep L3DATA in 3-state,
L3MODE must be kept LOW during the whole period
that reset signal at pin RESET is asserted; meanwhile,
no transfers can be performed (L3CLK stays HIGH).
2. For a proper initialization of the L3 interface logic of the
SAA2501, it is mandatory to make L3MODE HIGH and
LOW again after the device reset has been
de-activated. This must be done before any L3
transfer, even to or from other devices than the
SAA2501, is performed. Figure 14 shows that L3CLK
stays HIGH during this step.
3. Now the first transfer can be performed on the L3 bus.
This transfer must be a operational address (indicated
in Fig.14 by L3MODE = 0), addressing any of the
devices connected to the L3 bus. The first transfer to
the SAA2501 itself must always be either the writing of
a control word or the reading of the SAA2501 status;
the first transfer may never be a data item byte
transfer.
Remark: any deviation from these steps may result in
illegal L3 protocol behaviour of the SAA2501, even with
the possibility of disturbing transfers to other devices
connected to the L3 bus.
7.20.4 L3 INTERFACE CONTROL
The control of the SAA2501 L3 interface is performed with
one-byte control words. Status polling is not necessary
before writing control bytes. After writing the SAA2501
‘write control’ operational address, one or more control
bytes may be written. Each written control byte overrules
the previously sent control byte.
Table 15 L3 control
7
CTRL7
6
CTRL6
5
CTRL5
4
CTRL4
3
CTRL3
2
CTRL2
1
CTRL1
0
CTRL0
The definitions of the control bytes (CTRL7 to CTRL0) are given in Table 16.
Table 16 Explanation of control bytes
CTRL7 TO CTRL0
00000000
00000001
00000010
00000011
00000100
00000101
00000110
00000111
00001000 to 11111111
DEFINITION
read/write SAA2501 settings item
read decoded frame header item
read used frame header item
read error report item
reserved
read Ancillary Data item
write APU coefficients item
continue previous transfer
reserved
TYPE⁽¹⁾
I
I
I
I
I
I
I
C
−
Note
1. Control bytes of type I initiate the transfer of a data item. The control byte of type C may be used after interrupting a
transfer, in order to write APU coefficients, to return to the interrupted transfer.
January 1995
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