Cirrus Logic CS4297A - Manual (Page 30)

CS4297A
30
4.19 S/PDIF Control Register (Index 68h)
SPEN S/PDIF Enable. The SPEN bit enables S/PDIF data transmission on the S/PDIF_OUT pin.
The SPEN bit routes the left and right channel data from the AC ’97 controller, the digital mix-
er, or the digital effects engine to the S/PDIF transmitter block. The actual data routed to the
S/PDIF block is controlled through the AMAP/SM[1:0] configuration in the AC Mode Control
Register (Index 5Eh).
Val Validity. The V bit is mapped to the V bit (bit 28) of every sub-frame. If this bit is ‘0’, the signal
is suitable for conversion or processing.
Fs Sample Rate. The Fs bit indicates the sampling rate for the S/PDIF data. The inverse of this
bit is mapped to bit 25 of the channel status block. When the Fs bit is ‘clear’, the sampling
frequency is 48 kHz. When ‘set’, the sampling frequency is 44.1 kHz. The actual rate at which
S/PDIF data are being transmitted solely depends on the master clock frequency of the
CS4297A. The Fs bit is merely an indicator to the S/PDIF receiver.
L Generation Status. The L bit is mapped to bit 15 of the channel status block. For category
codes 001xxxx, 0111xxx and 100xxxx, a value of ‘0’ indicates original material and a value of
‘1’ indicates a copy of original material. For all other category codes the definition of the L bit
is reversed.
CC[6:0] Category Code. The CC[6:0] bits are mapped to bits 8-14 of the channel status block.
Emph Data Emphasis. The Emph bit is mapped to bit 3 of the channel status block. If the Emph bit
is ‘1’, 50/15us filter pre-emphasis is indicated. If the bit is ‘0’, no pre-emphasis is indicated.
Copy Copyright. The Copy bit is mapped to bit 3 of the channel status block. If the Copy bit is ‘1’
copyright is not asserted and copying is permitted.
/Audio Audio / Non-Audio. The /Audio bit is mapped to bit 1 of the channel status block. If the /Audio
bit is ‘0’, the data transmitted over S/PDIF is assumed to be digital audio. If the /Audio bit is
‘1’, non-audio data is assumed.
Pro Professional/Consumer. The Pro bit is mapped to bit 0 of the channel status block. If the Pro
bit is ‘0’, consumer use of the audio control block is indicated. If the bit is ‘1’, professional use
is indicated.
Default 0000h
For a further discussion of the proper use of the channel status bits see application note AN22: Overview of Digital
Audio Interface Data Structures [3].
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
SPEN Val 0 Fs L CC6 CC5 CC4 CC3 CC2 CC1 CC0 Emph Copy /Audio Pro
30 DS318PP6
CS4297A