User Guide

PAMS Technical Documentation 3. System Module
NSD-5
Issue 1 05/02 Nokia Corporation Page 39
VIN Charging input
L_GND Charging ground
IR Interface
If the phone supports internal infrared connection, the phone is set manually to infrared
mode, via the user interface SW selection. This is the only way to configure the phone for
the infrared mode. The infrared connection is always a point-to-point connection.
Once the infrared mode is selected, the phone begins to operate via the infrared connec-
tion using the IrDA protocol.
The disconnection of the infrared mode also is a manual operation involving the user
interface SW selection. If another accessory using cable is connected to the phone when
the phone is in infrared mode, that accessory is disregarded until the phone has been
disconnected from the infrared mode.
Audio Accessories
There are two types of audio accessories: headset and plug-and-play hands-free car kit.
XIMCP, XMICN, XEAR, and SGND are signals used for the external audio accessories.
XMICP and XMICN provide the differential input from the external microphone to the
CAFE. XEAR signals ended audio output to the external speaker. SGND is the ground for
the external speaker.
The headset accessory is simple to use. It consists of only an earpiece, a microphone, and
a HOOK-switch button, which can be used to answer a call or to end a call. The level of
signal HOOKINT can detect the status of the HOOK. When the button is pushed, a nega-
tive pulse is generated at HOOKINT to inform MCU that there is an interrupt from exter-
nal audio accessory to initiate or terminate a call.
The plug-and-play hands-free car kit is an active audio accessory that contains an inte-
grated loudspeaker and an option to connect an external microphone (unless the phone’s
built-in microphone is used).
The HF_MUTE signal is used to mute the external HF speaker.
A balanced configuration is used for the headset, which is accomplished by using two
1 kOhm for biasing the microphone.
When a headset is connected to the phone, EAD_HEADINT is pulled up since the spring
contact on the jag is open. MCU then checks the level on the EAD line through the
CCONT to determine which kinds of accessories are connected.
When a plug-and-play hands-free unit is connected, the voltage EAD is higher since
there is no microphone inside the plug-and-play and the plug-and-play provides approx-
imately 2.1 to 2.7 Vdc voltage to the XMICP. Depending on the status of the external
microphone for the plug-and-play, the MCU determines whether to use the built-in