Sony Ericsson GR47/GR48 User Manual
Page 34
5. SYSTEM CONNECTOR INTERFACE
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LZT 123 7589 R1A
5.8.1 PCM Data Format
All of the radio device’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 synchronisation) are both
generated by the DSP within the radio device.
The DSP within the radio device is the master therefore all external PCM
clocks and data from external devices must be synchronized to it
13-Bit PCM Mode
The radio device implements 13-bit PCM with the 13-bit data embedded
in a 16-bit word within a 24-bit frame (see Figure 5.8). 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 5.7
below.
Figure 5.7 16-bit data word format
16-Bit PCM Mode
The frame format is equal to the one shown in Figure 5.7, but with D15,
D14 and D0 filled with significant bits. D15 to D0 is the two’s
complement 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