Sony Ericsson GM47 - Manual (Page 53)

2. SYSTEM CONNECTOR INTERFACE
53
LZT 123 7263 R1C
2.7.1 PCM Data Format
All of the module’s PCM signals, including signals between its CODEC
and DSP conform to the PCM data I/O format of the industry standard
DSP from Texas Instruments.
PCMCLK (bit clock) and PCMSYNC (frame syncronisation) are both
generated by the DSP within the module.
The DSP within the module is the master therefore all external PCM
clocks and data from external devices must be synchronized to it
13-Bit PCM Mode
The module implements 13-bit PCM with the 13-bit data embedded in
a 16-bit word within a 24-bit frame (see Figure 2.6). Each PCM word
contains 16-bits: D0 to D15. D13 to D1 is the two’s complement value
of the 13-bit PCM, with D13 as the sign bit. D14 and D15 are always
set to be equivalent with D13. D0, the LSB, is not used as shown in
Figure 2.5 below.
Figure 2.5 16-bit data word format
16-Bit PCM Mode
The frame format is equal to the one shown in Figure 2.5, but with D15,
D14 and D0 filled with significant bits. D0 is the two’s compliment
value of the 16-bit PCM with bit 15 as the sign bit.
Bit Contents
D15 to D14 Equal to D13
D13 to D1 Two's complement of the 13-bit PCM
D0 LSB, not used
MSB D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 LSB
16 bit data word
13 bit PCM = D13 D0
Bit Contents
D15 - D0 Two's complement