User Guide

Figure 34 Bluetooth interface

The Bluetooth has a separate built in antenna and is powered by VBAT and the regulated voltage VIO. For

audio applications the Bluetooth has a PCM data bus. In addition a UART (universal asynchronous receiver/

transmitter) is used for data communication and controls.

FM radio

The FM radio is physically integrated with the Bluetooth into one single module. From a functional point of

view they, however, have nothing in common.

Figure 35 FM interface

The FM radio is an integrated circuit, controlled by MCU software through a serial bus interface. The wires of

the headset are used as poles of the antenna, and no other antenna is needed for FM radio reception.

In addition to the Bluetooth unit the FM radio is provided with LDO (low drop out) voltage 2V8_FM_LCD.

RM-396

System Module Description

Page 5 –18 COMPANY CONFIDENTIAL Issue 1