User Guide

RAE-6/RA-4

Nokia Customer Care 6 - Baseband Description and Troubleshooting

26 COMPANY CONFIDENTIAL Issue 1 12/04

bus. A third function provided by ACI is to identify and authenticate a specific accessory which

is connected to the system connector interface.

All accessories cause headint interrupt when connected to or disconnected from the system

connector. The insertion of an accessory generates a Headint interrupt by pulling the ACI line

down. When no accessory is present, the UEMEK’s internal Headint pull-up resistor keeps the

line high

All accessories have common detection start sequence, when phone gets headint interrupt

from high to low transition in ACI pin.

VOUT (Accessory Voltage Regulator)

UEMEK internal regulator is needed for accessory power supply purposes. All ACI-accessories

require this power supply.

■ HookInt

The hook signal is generated by creating a short circuit between the headset microphone sig-

nals. In this case, an LP-filter is needed on the HookInt input to filter the audio signal. When no

accessory is present, the HookInt signal is pulled up by the UEM resistor. When the accessory

is inserted and the microphone path is biased the HookInt signal decreases to 1.8V due to the

microphone bias current flowing through the resistor. When the button is pressed the micro-

phone signals are connected together, and the HookInt input gets half of micbias DC value 1.1

V. This change in DC level will cause the HookInt comparator output to change state, in this

case from 0 to 1. The button can be used for answering incoming calls but not to initiate outgo-

ing calls.

DC-plug

RAE-6/RA-4 uses a 3.5mm DC-plug. 3-wire chargers are supported, but 3-wire charging is not.

In practice this means that the 3-wire chargers are internally connected (charger control wire

connected to GND) as 2-wire chargers. 1Hz PWM signal is used to control UEMEK's charge

switch.

VCHAR pins of system connector

The VCHAR and ChargeGND pin are directly connected to the normal charger lines of the DC-

plug.