MC72000 Freescale Semiconductor, MC72000 Datasheet - Page 147

• Manufacturer Part Number: MC72000
• Description: Integrated Bluetooth Radio
• Manufacturer: Freescale Semiconductor

10.9 Audio
A key feature of Bluetooth is its native quality-of-service (QoS) supporting audio at both the link and
application levels. A key component of Motorola’s approach to delivering high quality audio over
Bluetooth is the Bluetooth Audio Signal Processor (BTASP) that has been designed into the MC72000.
The Bluetooth Audio Signal Processor (BTASP) is a dedicated module that handles all
computation-intensive audio functionality in a Bluetooth system. Bluetooth supports voice links
compressed with either log-PCM (A-law or µ-law) or CVSD. A voice link is duplex and the data rate is
fixed at 64 kbit/s.
Four different packet types are defined: HV1, HV2, HV3 packets with 10, 20, or 30 bytes of encoded
audio, and DV packets with 10 bytes of encoded audio and up to 9 bytes of ACL data. SCO packets are
single-slot packets sent at fixed intervals. Multiple simultaneous SCO links are possible if HV2 or HV3
packets are used.
Powerful 6th order IIR filtering will band limit the signal according to the Bluetooth requirements. 60dB
stop band attenuation is easily achieved. This is important to avoid imaging and aliasing in the up/
down-sampling. The audio quality is significantly better when compared to a 4th order IIR filter. The IIR
filter also provides extremely low audio latency that is essential in many applications. In duplex
applications, such as a headset, a too high latency may necessitate the use of echo cancellers. The filter
noise floor is close to -100dB, and will not degrade the quality possible within the Bluetooth audio
specification.
The included DC blocker will remove any potential DC-offset from the signal in order to minimize packet
loss effects.
The Bluetooth clock and the CODEC sample clock are not synchronous and may drift. Therefore, it is
necessary to synchronize data to/from a CODEC with the Bluetooth clock. For this reason, the BTASP
includes a second order interpolation algorithm. The interpolator provides a way to stretch or compress the
number of available samples to what is needed, providing a quality far superior to simpler synchronization
schemes such as repeating or discarding samples. The setup and control of the interpolator is handled by
software so the synchronization and choice of CODEC is highly flexible.
The BTASP implements all signal processing needed to support a maximum of three simultaneous audio
links using all the defined compression/decompression standards. The BTASP will also handle Bluetooth/
CODEC synchronization.
MOTOROLA
ATMEL AT25640
ATMEL AT25320
Microchip 25640
ST M95320
ST M95640
ST M95128
ST M95256
Type
Freescale Semiconductor, Inc.
For More Information On This Product,
MC72000 Advance Information Data Sheet
Table 68. EEPROMs (Continued)
Go to: www.freescale.com
Preliminary
16 kBytes
32 kBytes
8 kBytes
4 Kbytes
4 kBytes
8 kBytes
8 kBytes
Size
Applications Information
1.50 MHz
1.50 MHz
1.50 MHz
1.50 MHz
1.50 MHz
1.50 MHz
1.50 MHz
Speed
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