Audio Function Partitioning - Sierra Wireless MC5725 Hardware Integration Manual

CDMA and GSM / UMTS Mini Card Hardware Integration Guide
58
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
Table 4-4: Primary audio signal interface
Signal Pin #
SPK_P 5
SPK_N 7
Table 4-5: PCM digital audio signal interface
Signal Pin #
45
PCM_CLK
PCM_DIN 47
PCM_DOUT 49
PCM_SYNC 51

Audio function partitioning

These phone‐oriented functions are usually under module
control:
FIR filters—both transmit and receive path
•
Noise suppression—required due to high sensitivity and
•
gain in transmit path
Echo cancellation—different for each audio path and
•
environment (handset, headset, car kit, speakerphone)
• High pass filtering / slope filtering functions—required per
phone acoustic requirements
• AGC (Automatic Gain Control)—normalizes audio
volumes in varying acoustic environments
DTMF tones—the generation and detection of DTMF tones
•
is required in both directions of the phone interface
Comfort noise—low level noise injected into receiver path
•
for user ʺconnectionʺ experience
Simple ringers—digital and analog tones, melody ringers,
•
MIDI with limited memory storage
These functions are typically performed in the host codec:
Voice Memo—performed by the host if significant memory
•
storage is required
Polyphonic ringtone—host often supports WAV, MIDI
•
formats with significant memory storage
Audio path switching—turn on audio path depending on
•
user interface selection, or headset detection
Proprietary and Confidential
Type Directions
Analog Output
Analog Output
Type Directions
Digital Output
Digital Input (internal
pull-down)
Digital Output
Digital Input (internal
pull-down)
Description
Non-inverted
speaker output (+)
Inverted speaker
output (-)
Description
PCM clock
PCM data in
PCM data out
PCM sync
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