Nokia NKC-1X Series, Technical Documentation Manual

Page: 21 / 54

CCS Technical Documentation System Module
NKC-1X
Issue 1 02/03

Nokia Corporation Page 21
Accessories Interface
System connector
Introduction
NKC-1X uses accessories via a system connector.
Interface
The interface is supported by fully differential 4-wire (XMICN, XMICP, XEARN and
XEARP) accessories. NKC-1X supports the HDE-2 inbox headset, HDB-5 Boom Headset,
HDC-5 headset, LPS-3 loopset and the PPH-1 car kit.
Figure 6: System Connector
An accessory is detected by the HeadInt- line, which is connected to the XEARP inside
the system connector. When an accessory is connected, it disconnects XEARP from
HEADINT, and the UEM detects it and generates an interrupt (UEMINT) to the MCU. After
that, the HOOKINT line is used to determine which accessory is connected. This is done
by the voltage divider, which consists of the phone's internal pull-up and accessory-spe-
cific pull-down. The voltage generated by this divider is then read by the ad- converter of
UEM. The HOOKINT- interrupt is generated by the button in the headset or by the acces-
sory external audio input.
VIN
XMICP
MICN MIC
GND
XMICN
HF
HEADINT HFC
PWMO