User Guide

RH-42
System Module CCS Technical Documentation
Page 20 Nokia Corporation Confidential Issue 2 09/2003
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.
Figure 7: Accessory Detection / External Audio
VIN
XMICP
MICN MIC
GND
XMICN
HF
HEADINT HFC
PWMO
2k2
Hookint
HeadintHeadint
EAD
MIC1Bias
MIC1P
MIC1N
33n
HFCM
HF
UEM
2.1V
2.7V
33n
/MBUS
MicGND
1.8V
0.3V
0.8V
3...25k
100
p