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There are several major blocks in the signal flow block diagram:
Microcontroller
Codec
DSPs
DSP boot PROM
EEPROM
Switch-mode
Power Supply
5V power supply
1.3
Control Interface Overview
The control interface consists of a serial data input and a serial data output. The input data
stream must comply with OP173549 (CD-5) or use a 5V 4800 baud format. The output
consists of command acknowledgments, error codes, etc., and is always 5V 4800 baud
RS-232.
RS-232 should be used for testing, since 1.) it is easy to generate and 2.) the CD-5 data
protocol does not easily accommodate special test commands (i.e., anything beyond what
is required for normal product operation).
Commands include:
• any normal product function (volume up/dn, mute/unmute, etc.)
• query software revision
• read microcontroller ADC ports
• alter/display EEPROM contents
• alter/display codec registers
• alter/display DSP memory
• reset DSPs
Framingham, MA 01701-9168
The microcontroller manages the serial data interface the outside
world and the DSP signal processing system, mutes and un-mutes
the power amplifiers, stores and retrieves EEPROM data, and mon-
itors temperature and other indicators of bassbox health.
The codec integrates the input ADCs, the input SPDIF receiver, and
the output DACs into one IC.
All signal processing is performed by the DSPs: AC-3 decode, vid-
eostage decode, bass management, volume control, speaker
equalization, dynamic equalization, etc.
Unlike the microcontroller, the DSPs have no non-volatile memory
and must boot from external PROM. Any changes to the signal pro-
cessing code (e.g., new speaker eq. curves) would require a new
PROM.
Used to store system variables which need to survive a power cy-
cle, e.g., the speaker eq. configuration and the date of manufacture.
Regulates the +17V raw DC rail down to 3.3V @350mA for the
DSPs.
Regulates the +17V raw DC rail down to 5V @ 100mA for the codec
and microcontroller.
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