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User Guide

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PAMS
Technical Documentation
NSB–1
System Module
Original 06/98
Page 3 – 16
Real time clock
Requirements for a real time clock implementation are a basic clock
(hours and minutes), a calender and a timer with alarm and power on/off
–function and miscellaneous calls. The RTC will contain only the time
base and the alarm timer but all other functions (e.g. calendar) will be im-
plemented with the MCU software. The RTC needs a power backup to
keep the clock running when the phone battery is disconnected. The
backup power is supplied from a rechargable polyacene battery that can
keep the clock running some ten minutes. If the backup has expired, the
RTC clock restarts after the main battery is connected. The CCONT
keeps MCU in reset until the 32kHz source is settled (1s max).
The CCONT is an ideal place for an integrated real time clock as the asic
already contains the power up/down functions and a sleep control with
the 32kHz sleep clock, which is running always when the phone battery is
connected. This sleep clock is used for a time source to a RTC block.
Signals between baseband and User Interface section
The User interface section is implemented on separate UI board, which
connects to the engine board with a board to board spring connector.
User Interface module connection
The User interface section comprises the keyboard with keyboard lights,
display module with display lights, an earphone and a buzzer.
Earphone
The internal earphone is connected to the UI board by means of mount-
ing springs for automatic assembly. The low impedance, dynamic type
earphone is connected to a differential output in the COBBA audio codec.
The voltage level at each output is given as reference to ground. Ear-
phone levels are given to 32 ohm load.
Buzzer
Alerting tones and/or melodies as a signal of an incoming call are gener-
ated with a buzzer that is controlled with a PWM signal by the MAD. Also
key press and user function response beeps are generated with the buzz-
er. The buzzer is a SMT device and is placed on the UI board.