GR47/48 Design Guidelines
BA/SEM/MS 03:0015 Rev A
LZT 123 7596
15
3.5 Audio Connections
Audio connections for both of the analogue paths are shown below.
3.5.1 Analogue Audio
Pin
Signal
Dir.
Description
57
AFMS
O
Audio From Mobile Station
59
ATMS
I
Audio To Mobile Station
60
AGND
-
Ground (return) for analogue audio
ATMS and AFMS are the audio input and output for the module.
Figure 3.3 shows the connection of the analogue audio signals ATMS
and AFMS to the CODEC. An Advanced Portable Hands Free
accessory is also shown to clarify the connections.
Simplified Circuit
CODEC
ATMS
MIC
AGND
AFMS
Audio Out
<20 ohms
Bias
0V or 2V or 2.5V
Audio In
70K Ohms
2.7K
Switch
2.2u
Speaker
GM47
Figure 3.3. Analogue Audio Signal Connections.
It is possible to use the analogue audio signals in different modes.
•
Hands-Free - This is the state referred to as Audio To Mobile
Station ATMS and Audio From Mobile Station AFMS, which
will be used by audio accessories like handsets or Hands Free
equipment.
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