PS-SAU-1900E
Mar. 8
th
,1999 (Rev. 0.0)
--- CONFIDENTIAL AND PROPRIETARY ---
30
3.2.1.
Line Interface Module.
The Line Interface Module provides the hardware voice and data interface between the external
telephone device and the Qualcomm MSM. The LIU control software must support these functional
requirements.
1.
Configuration and state control signaling for the LIU SLIC device. The parameters which are set
include:
•
Loop Start / Ground Start operation.
•
Loop voltage level (on hook or off hook)
•
Ringing state.
•
Forward Disconnect control.
•
Low Power Scan mode.
2.
Hook switch status sensing.
3.
Conversion of digital Caller Identification information into analog data, which is then transmitted
across the analog interface.
3.2.1.1. SLIC
Operation.
The SLIC has four inputs for control; B0, B1, B2, BR. These 4 lines control what state the SLIC is in.
The possible states for the SLIC are:
B0 B1 B2 BR
State
1
1
0
1
Power Up Forward -24 V
1
0
0
1
Power Up Reverse -24 V
1
1
1
1
Power Up Forward -65 V
1
0
1
1
Power Up Reverse -65 V
0 1 1 1
Ground
Start
0
1
1
1
Low Power Scan
0 X 0 1
Forward
Disconnect
1 X 1 0
Ring
State
Values in
italics
are initial conditions at power-up.
The SLIC is initialized to Low Power Scan, at unit power up. When the phone is on hook in the idle state
the SLIC will be in Low Power Scan. When the phone goes off hook (either originating or answering
incoming call), the SLIC will be in Power Up Forward -24 V (the -24 V and -65 V inputs are outputs of the
power supply board which is explained later).
When alerting for an incoming call the SLIC will go to the Ring State. The ringing of the phone is
controlled by a 20 Hz square wave output on B1, the normal ring cadence is 2 seconds on, 4 seconds
off. Different ring cadences are available, and are selected via switches within the MSM controller
software, or by commands received over the J-STD-008 air interface.
The MSM accepts the Off Hook Int output of the SLIC card as and input into the Keysense 0 pin (normally
used to sense a keypress on the mobile to set off an interrupt to wake the phone from Sleep mode).
This Off Hook Int output is High when the phone is on hook and goes to Low when the phone is off hook
(the off hook low transition is not a transient). The interrupt is called so the incoming call alert (phone
