User's Manual

M80 Hardware Design
M80_HD_V1.2 - 64 -
3.13. PCM interface
M80 supports PCM interface. It is used for digital audio transmission between the module and the
customer’s device. This interface is composed of PCM_CLK, PCM_SYNC, PCM_IN and
PCM_OUT signal lines.
Pulse-code modulation (PCM) is a converter that changes the consecutive analog audio signal to
discrete digital signal. The whole procedure of Pulse-code modulation contains sampling,
quantizing and encoding.
Table 21: Pin definition of PCM interface
Name
Pin NO.
I/O
Description
Note
PCM_CLK
19
O
PCM clock
PCM_IN
18
I
PCM data input
PCM_OUT
20
O
PCM data output
PCM_SYNC
21
O
PCM frame synchronization
3.13.1. Configuration
M80 supports 13bit line code PCM format. The sample rate is 8 KHz, the clock source is 256 KHz,
and the module can only act as master mode. The PCM interfaces support long and short
synchronization simultaneously. It only supports MSB first. For more detailed information, please
see the table below.
Table 22: Configuration
PCM
Line interface format
Line
Data length
Line：13bit
Sample rate
8KHz
PCM clock/synchronization
source
PCM master mode: clock and synchronization is generated
by module
PCM synchronization rate
8KHz
PCM clock rate
PCM master mode:256 KHz(line)
PCM synchronization format
Long/short synchronization
PCM data ordering
MSB first