Wolfson WM8804 - S;Pdif Transmitter

Production Data WM8804
w
PD Rev 4.1 September 2007
31
S/PDIF TRANSMITTER
The S/PDIF transmitter generates the S/PDIF frames, and outputs on the TX0 pin. The transmitted
data can be sourced from one of two places, selectable using the TXSRC register. The transmitter
can be powered down using the SPDIFTXD register bit.
REGISTER
ADDRESS
BIT LABEL DEFAULT DESCRIPTION
5 TXVAL_SF0 0 Overwrite Mode S/PDIF Transmitter Validity Sub-
Frame 0
0 = transmit validity = 0
1 = transmit validity = 1
6 TXVAL_SF1 0 Overwrite Mode S/PDIF Transmitter Validity Sub-
Frame 1
0 = transmit validity = 0
1 = transmit validity = 1
R6
PLL4
06H
7 TXVAL_
OVWR
0 S/PDIF Transmitter Validity Overwrite Mode Enable
0 = disabled, validity bit is 0 when the S/PDIF
transmitter sources PCM audio interface, or it matches
the S/PDIF input validity when the S/PDIF transmitter
sources the S/PDIF receiver.
1 = enabled, validity bit transmitted for subframe 0 is
defined by TXVAL_SF0, validity bit transmitted for
subframe 1 is defined by TXVAL_SF1.
6 TXSRC 1 S/PDIF Transmitter Data Source
0 = S/PDIF received data.
1 = Audio interface received data
R21
SPDTX4
15h
7 TXSTATSRC 0 S/PDIF Transmitter Channel Status Data Source
0 = Received channel status data
1 = Transmit channel status registers
Note 1: Only used if TXSRC=0
Note 2: See section User Data below
R30
PWRDN
1Eh
2 SPDIFTXPD 1
S/PDIF Transmitter Powerdown Enable
0 = S/PDIF transmitter enabled
1 = S/PDIF transmitter disabled
Table 33 S/PDIF Transmitter Control
The WM8804 also transmits the preamble and VUCP bits (Validity, User Data, Channel Status and
Parity bits).
VALIDITY BIT
By default, set to 0 (to indicate valid data) with the following exceptions:
1. TXSRC=0 (S/PDIF receiver), where Validity is the value recovered from the S/PDIF input
stream by the S/PDIF receiver.
2. TXVAL_OVWR=1, where Validity is the value set in registers TXVAL_SF0 and TXVAL_SF1.
USER DATA
Set to 0 as User Data configuration is not supported in the WM8804 – if TXSRC=0 and TXSTATSRC
=0 (S/PDIF receiver) User Data is set by the receiver.