User's Guide

The Hardware View SB300 Series
Page 92 Proprietary and Confidential 2110059 Rev 1.1
10.4.6.2. Wireline and Voice Interface
The SB320 provides a 13-pin I/O connector for its wireline interface to the PSTN and for the
voice mode connections to a microphone and speaker (headset or handset). The connector is
positioned on the opposite end of the housing from the serial host (DTE) connector. This
connector provides these interfaces:
1. Telephone Line Interface
2. Voice Feature Interface
3. Status Outputs 1 and 2
The connector pinouts are specified in Table 10-9. Specific configuration detail for the different
interfaces follow. Signal types are with respect to the modem (DCE).
Table 10-9: Pinout of Wireline and Voice Connector
Pin number Signal Name Type Description
1 Reserved Leave Unconnected
2 SPKR– Output Speaker Interface negative
3 SPKR+ Output Speaker Interface positive
4 MIC+ Input Microphone Interface positive
5 MIC– Input Microphone Interface negative
6 – 7 Reserved Input Leave Unconnected
8 \STATUS_OUT1 Output Power + RF Channel Status
9 \STATUS_OUT2 Output Transmitter
10 GROUND Ground Signal Ground
11 Reserved Leave Unconnected
12 RING Input Wireline Connection
13 TIP Input Wireline Connection
Voice Feature Interface
Speaker Output
The speaker output is a differential signal used to interface to a speaker amplifier, headset, or
handset. The output signal is AC-coupled through 4.7µF capacitors.
The table below co-relates the output voltage with some sample gain settings.
AT+WVRAGC= AT+WVRVL=
Output Voltage (mV
p-p
)
3 9 28 – 190
2 9 24 – 160
7 9 7 – 20
In circuit-switched and wireline data modes this signal is used to indicate call progress.
Microphone Input
The microphone input is a differential signal used to interface to an electret microphone for voice
applications. The input signal is under a 4.71 kΩ load. Nominal input is 9 mV
p-p
. Higher input
levels, up to 100 mV
p-p
, can be used with the gain control settings near their minimum:
+WVXAGC=4 and +WVXVL=1.
For developers who desire a single-ended microphone input, the MIC– signal can be connected to
GND.