DSB45 Development Support Box
Confidential / Released
s
DSB45_HD_V05
Page 22 of 50
01.02.2008
2.7.5.2
Audio interface 2 (for handsfree operation)
The audio interface 2 is designed for testing handsfree operation.
All lines of the second audio interface, microphone and loudspeaker, are balanced. The
loudspeaker lines of the GSM module have a DC offset, for details see [1].
The audio interface 2 of DSB45 does not include a microphone power supply. The power for
the microphone is supplied by the GSM module.
The DSB45 provides two solutions to connect an audio device to audio interface 2. Both
solutions are mutually exclusive:
•
12-pin Lumberg connector X603 if the audio slide switches X127 – X130 are set to
position “on”. Pins 1 – 3 of the X603 connector are dedicated for a battery charger. If the
X603 connector is enabled, the pins 33 – 36 of the X153 connector are available for
measuring.
Example: A suitable handsfree device is the Siemens Car Kit Portable.
•
Test pins 33 – 36 of the X153 connector if the audio slide switches X127 – X130 are set
to position “off”. Position “off” disables the X603 connector.
Table 9: Pin assignment of audio interface 2
Signal name I/O
Description
Pin at X603 and slide
switch positions
Pin at X153 and slide
switch positions
MICP2
I
Microphone plus
Pin 9
X130 = on Pin 33
X130 = off
MICN2
I
Microphone minus
Pin 10
X129 = on Pin 34
X129 = off
EPP2
O
Loudspeaker plus
Pin 11
X128 = on Pin 35
X128 = off
EPN2
O
Loudspeaker minus
Pin 12
X127 = on Pin 36
X127 = off
Figure 9: Siemens Car Kit Portable
