FM Transmitter Component Overview

This document provides an overview of the FM transmitter.

Purpose

The FM transmitter is an independent component, which provides control APIs for the applications to control the FM transmitter in a device.

Required background

The FM transmitter transmits the audio as FM radio signal, which can be received by appliances, such as a car stereo.

The FM transmitter component provides APIs to control the transmitter. A reference transmitter plug-in is also provided to map the control APIs to the Hardware Resource Manager (HWRM) API. The FM transmitter is designed in a similar way to theFM tuner API.

Architectural relationships

The FM transmitter is a component of Multimedia API and Framework Collection. The Transmitter consists of a Transmitter Utility and Transmitter Plug-in as shown in diagram.

Figure 1. FM Transmitter Architecture diagram

MMTransmitterUtility provides an API for applications to configure the transmitter, scan for clear frequencies and set the RDS Data.

When you provide an implementation of the FM Transmitter functionality you must provide Info-Plug-in. Info-Plug-in implements the MMMTransmitterInfo interface to list the transmitters available in the system and associated capabilities.

The Transmitter Plug-in implements the actual transmission functionality using the MMMTransmitterUtility interface, the MMMRdsTransmitterUtility and the MMMTransmitterScannerUtility.

API summary

The FM transmitter component includes the following APIs:

Client API

API Description

CMMTransmitterUtility

This represents the FM transmitter.

CMMTransmitterScannerUtility

This forms the scanning utility API.

CMMRdsTransmitterUtility

This forms the RDS utility API.

These classes define the FM Transmitter. If the client requires an FM function, it accesses it through these clients APIs.

Plug-in API

The interface classes are MMMTransmitterUtility, MMMTransmitterInfo, MMMTransmitterScannerUtility, and MMMRdsTransmitterUtility. Plug-ins that provides an implementation of the transmitter must implement the interface classes.

Typical uses

FM transmitter can be used to do the following:

  • Control FM transmission in a device. For example, an audio player application can enable and control audio transmission.

  • Transmit RDS data and scan for clear frequencies without interference.

  • Provide access to multiple clients and prioritize them.