User Guide

PAMS
Technical Documentation
NSB–1
System Module
Page 3 – 21
Original 06/98
Power Off
The baseband is powered down by:
1. Pressing the power key, that is monitored by the MAD, which
starts the power down procedure.
2. If the battery voltage is dropped below the operation limit, ei-
ther by not charging it or by removing the battery.
3. Letting the CCONT watchdog expire, which switches off all
CCONT regulators and the phone is powered down.
4. Setting the real time clock to power off the phone by a timer.
The RTC generates an interrupt signal, when the alarm is gone
off. The RTC interrupt signal is connected to the PWRONX line
to give a power off signal to the CCONT just like the power key.
The power down is controlled by the MAD. When the power key has been
pressed long enough or the battery voltage is dropped below the limit the
MCU initiates a power down procedure and disconnects the SIM power.
Then the MCU outputs a system reset signal and resets the DSP. If there
is no charger connected the MCU writes a short delay to CCONT watch-
dog and resets itself. After the set delay the CCONT watchdog expires,
which activates the PURX and all regulators are switched off and the
phone is powered down by the CCONT.
If a charger is connected when the power key is pressed the phone en-
ters into the acting dead mode.
Audio control
The audio control and processing is taken care by the COBBA, which
contains the audio and rf codecs, and the MAD, which contains the MCU,
ASIC and DSP blocks handling and processing the audio signals.
Microphone and Earphone
The baseband supports three microphone inputs and two earphone out-
puts. The inputs can be taken from an internal microphone, a headset mi-
crophone or from an external microphone signal source. The microphone
signals from different sources are connected to separate inputs at the
COBBA asic. Inputs for the microphone signals are differential type.
The output for the internal earphone is a dual ended type output capable
of driving a dynamic type speaker. The output for the external accessory
and the headset is single ended with a dedicated signal ground SGND.
Input and output signal source selection and gain control is performed in-
side the COBBA asic according to control messages from the MAD. Key-
pad tones, DTMF, and other audio tones are generated and encoded by
the MAD and transmitted to the COBBA for decoding.