User Guide

NSM–3/3D
UI Module
PAMS Technical Documentation
Page 9
Issue 3 11/2000
 Nokia Mobile Phones Ltd.
will assume that some accessory is connected. In XMICN signal there is a
1.2 kW pulldown in transceiver and serial 1.2 kW from AUXOUT to XMICP.
The XMICN is connected to transistor which is then connected to the
HookDet line (in MAD).
External accessory notices powered–up phone by detecting voltage in
HeadDet line.
Accessory connected HookDet*) HeadDet**) Notes
No accessory connected High Low
Headset with a button switch pressed Low High XEAR and XMIC loaded (dc)
Headset with a button switch released High High XEAR and XMIC loaded (dc)
Handsfree (PPH–1) Low High XMIC loaded (dc)
*) HookDet is used only for detect button in headset
**) HeadDet is used only for detect that some accessory is connected into sys-
tem connector
NOTE: Charging must stop when the detection sequences is done! CCUT
signal at high stops charging.
Headset detection
The external headset device is connected to the headset connector, from
which the signals are routed to COBBA headset microphone inputs and
earphone outputs. In the XMICN line there is a 1.0 kW pulldown in the
transceiver. The microphone is a low resistance pullup compared to the
transceiver pulldown.
When there is no call going, the AUXOUT is in high impedance state and
the XMICN and XMICP is pulled down. When a headset is connected, the
XMICP is pulled up. The switch inside the system connector is connected
to the HeadDet line (in MAD), an interrupt is given due to both connection
and disconnection.
NOTE: If the headset is connected switch closed the transceiver can not
detect if headset or PPH–1 in power off mode is connected. When switch
is released to open transceiver can not any more detect the headset with-
out polling by SW.
Headset switch detection
In the XMICN line there is a 1.0 kW pulldown in the transceiver. The mi-
crophone is a low resistance pullup compared to the transceiver pull-
down. When a remote control switch is open, there is a capacitor in paral-
lel with the microphone, so the XMICN is pulled up and HookDet pulled
down by the phone, when AUXOUT is set to 2.1V. When the switch is
closed, the XMICN is pulled down via the microphone and HookDet is
pulled up. So both press and release of the button gives an interrupt
when AUXOUT is set to 2.1V.
PPH–1 detection
The external Plug & Play PPH–1 device is connected to the system con-
nector, from which the signals are routed to COBBA headset microphone