User Guide

NPE-4
3 - Audio System PAMS Technical Documentation
Page 3-30 ãNokia Corporation. Original
Accessory Detection, Identification and Control
Accessory Detection
Accessories are detected when the XMIC signal is loaded with either DLR3, Loopset or
Headset. The interrupt is generated by pulldown resistors in the respective accessories.
Carkit 91 is detected via communication on the MBUS line.
BT accessories are connected after BT connectivity is chosen in UI. Communication with
UEM is done over the CBUS lines.
Accessory Identification
The voltage on the XMICP is used to identify which type of accessories that are con-
nected to the system connector. See Table 16: HEADINT Voltage Value Table used for
Accessory Identification. The HEADINT interrupt is detected in the UEM and this voltage
level is used to determine the type of accessory.
A voltage is measured on the HeadInt input on the UEM. This signal is multiplexed to an
A/D converter in the UEM. From this level an Accessory server recognises the type of
accessory and chooses the relevant audio accessory tuning if applicable. If the detection
voltage window is as described in Table 16: HEADINT Voltage Value Table used for Acces-
sory Identification for headset and loopset the microphone bias is enabled.
If DLR3 is used the detection voltages are as in Table 16: HEADINT Voltage Value Table
used for Accessory Identification, no bias for the microphone is enabled and 2.8 V DC for
DLR3 is supplied.
Table 16: HEADINT Voltage Value Table used for Accessory Identification
ACCESSORY CONNECTED HEADINT
VOLTAGE LEVEL
NOTES
MIN MAX
Headset HDC-9P and Loopset LPS-1 19 mV 300 mV Without MBias
Varying with microphone FET
working line.
Carkit CARK-91 Detected and acknowledged by the
phone on MBUS
DLR3 300 mV 800 mV