In wired audio mode, if required, the headset is still available for Bluetooth audio. This enables seamless transition
from wired audio mode to Bluetooth audio mode and back again. This transition is configurable to occur automatically
as the battery voltage of the headset reduces to a point at which Bluetooth audio is no longer possible.
The additional development board CNS11010 enables support for the wired input mode and is available as part of
the development kit.
16.1.4
USB Modes Including USB Audio Mode
CSR8640 BGA supports a variety of USB modes which enables the USB interface to extend the functionality of a
CSR8640 BGA based stereo headset.
CSR8640 BGA supports:
■
USB charger enumeration
■
USB soundcard enumeration (USB audio mode)
■
USB mass storage enumeration
USB audio mode enables the headset to enumerate as a soundcard while charging from a USB master device,
e.g. a PC. In this mode, the headset enumerates as either a stereo music soundcard (for high quality music playback)
or a bidirectional voice quality soundcard. This enables the headset for either listening to music streaming from the
USB host device or for voice applications, e.g. Skype.
The USB audio mode operates at the same time as the wired audio mode and the USB audio interrupts the wired
audio mode if USB audio is attached. This enables a headset to have both wired audio and USB modes connected
at the same time.
In USB audio mode, if required, the headset is still available for Bluetooth audio.
16.1.5
Smartphone Applications (Apps)
CSR8640 BGA includes CSR’s proprietary mechanism for communicating with smartphone apps, it enables full
UI control of the headset from within the application running on a smartphone, e.g. Google Android OS-based
handset. For more information on this feature contact CSR.
16.1.6
Programmable Audio Prompts
CSR8640 BGA enables a user to configure and load pre-programmed audio prompts from:
■
An external EEPROM, in this implementation the prompts are stored in the same EEPROM as the PS
Keys, see Figure 16.2. A larger EEPROM is necessary for programmable audio prompts. This
implementation supports EEPROMs up to 512Kb. An EEPROM of 512Kb enables approximately 15
seconds of audio storage.
■
An external SPI flash, in this implementation the prompts are stored in the same SPI flash as the PS
Keys, see Figure 16.1.
The programmable audio prompts provide a mechanism for higher-quality audio indications to replace standard tone
indications. A programmable audio prompt is assigned to any user event in place of a standard tone.
Programmable audio prompts contain either voice prompts to indicate that events have occurred or provide user-
defined higher quality ring tones/indications, e.g. custom power on/off tones.
The Headset Configurator tool can generate the content for the programmable audio prompts from standard WAV
audio files. The tool also enables the user to configure which prompts are assigned to which user events.
Section 6.5 describes the SPI flash interface and Section 7.4 describes the I²C interface to an external EEPROM.
Advance Information
This material is subject to CSR's non-disclosure agreement
© Cambridge Silicon Radio Limited 2011
Page 94 of 110
CS-209182-DSP1
CSR8640 BGA
Data Sheet
