Bluetooth Audio Module
Ehong Technology Co., Ltd
Figure 7 : Audio Interface
The interface for the digital audio bus shares the same pins as the PCM codec interface
described in Table 11, which means each of the audio buses are mutually exclusive in their
usage. Table 11 lists these alternative functions.
PCM Interface
SPDIF Interface
I²S Interface
PCM_OUT
SPDIF_OUT
SD_OUT
PCM_IN
SPDIF_IN
SD_IN
PCM_SYNC
-
WS
PCM_CLK
-
SCK
Table 11: Alternative Functions of the Digital Audio Bus Interface on the PCM Interface
The audio input circuitry consists of a dual audio input that can be configured to be either
single-ended or fully differential and programmed for either microphone or line input. It has an
analogue and digital programmable gain stage for optimization of different microphones.
The audio output circuitry consists of a dual differential class A-B output stage.
6.9.1. PCM
The audio pulse code modulation (PCM) interface supports continuous transmission and
reception of PCM encoded audio data over Bluetooth.
Hardware on EH-MB18 allows the data to be sent to and received from a SCO connection. Up
to three SCO connections can be supported by the PCM interface at any one time.
EH-MB18 can operate as the PCM interface master generating PCM_SYNC and PCM_CLK or
as a PCM interface slave accepting externally generated PCM_SYNC and PCM_CLK.
EH-MB18 is compatible with a variety of clock formats, including Long Frame Sync, Short
Frame Sync and GCI timing environments.
