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DSB45 Development Support Box
Confidential / Released
2.7.5
Audio interfaces
DSB45 provides three audio interfaces:
•
Analog audio interface 1 designed for connecting a handset.
Accessible at the X502 connector or at the test pins 37 – 40 of the X153 connector.
•
Analog audio interface 2 designed for connecting a handsfree device.
Accessible at the X603 connector or at the test pins 33 – 36 of the X153 connector.
•
Digital audio interface designed for digital audio measuring.
Accessible at the X203 connector or at pins 25 - 30 of the external 40-pin connector
X152. MC55i supports only the X152 solution.
2.7.5.1
Audio interface 1 (for handset)
Audio interface 1 adapts the voltage level of the GSM module to a handset.
All lines of the first audio interface, microphone and loudspeaker, are balanced. The
loudspeaker lines of the GSM module have a DC offset, for details see [1].
The interface has been optimized for use with the reference handset type Votronic supplied
with the DSB45 Development Support Box. The Votronic handset is a passive handset.
Power supply for its microphone is provided by the DSB45 (5V over 2 x 2.2kΩ at pin 4 and
pin 1 of audio interface 1).
The DSB45 provides two solutions to connect an audio device to audio interface 1. Both
solutions are mutually exclusive:
•
4-pin Western jack X502 if the audio slide switches X123 – X126 are set to position "on".
Pins 37 – 40 of the X153 connector are available for measuring.
Example: The Votronic handset can be connected to X502.
•
Test pins 37 – 40 of the X153 connector if the audio slide switches X123 – X126 are set
to position "off". Position "off" disables the X502 connector.
The location of the X502 connector, the X153 connector and the audio slide switches can be
gathered from Figure 3.
Table 8: Pin assignment of handset audio interface 1
Signal name
I/O
MICN1
I
EPN1
O
EPP1
O
MICP1
I
The pin assignment of the Western jack is shown in Table 8, Figure 3 and Figure 8.
The Votronic handset is the reference handset used with DSB45. Acoustic approval of the
Siemens GSM module applies to the reference configuration comprising the Votronic
handset and the DSB45. For details refer to [1]. GSM applications that incorporate audio
devices other than the reference handset must be submitted for additional type approval.
DSB45_HD_V05
Description
Microphone minus
Loudspeaker minus
Loudspeaker plus
Microphone plus
Figure 8: 4-pin Western jack X502 on DSB45
Page 21 of 50
Pin at X502 and slide
switch positions
Pin 1
X125 = on
Pin 2
X123 = on
Pin 3
X124 = on
Pin 4
X126 = on
s
Pin at X153 and slide
switch positions
Pin 37
X125 = off
Pin 38
X123 = off
Pin 39
X124 = off
Pin 40
X126 = off
1 4
01.02.2008
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