For standard GSM voice a 13-Bit PCM data word is embedded in a 16-bit word frame, as shown in Figure 5.10-1 below.

sample LSB justified

MSB

LSB

D15 D0

13-bit sample occupies these frame bits

Figure 5.10-1 Typical 16-bit PCM Voice Sample Word Format

Typical PCM data transfer is shown in the following figures.

SSPCLK

 

 

 

SSPFS

 

 

 

SSPDTM

MSB

LSB

Q

SSPDFM

Q MSB

LSB

 

Figure 5.10-2 PCM Frame format for a single transfer

SSPCLK

 

 

 

 

SSPFS

 

 

 

 

SSPDTM

LSB

MSB

LSB

MSB

SSPDFM

LSB

MSB

LSB

MSB

Frame n-1

Frame n

 

Frame n+1

Figure 5.10-3 PCM Frame format for a continuous transfer

LZT 123 1836

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