Real Time Clock; Baseband Module; Technical Summary; Figure 6: Ir Tramsmission Frame - Example - Nokia NSB-5 Series Technical Documentation Manual

NSB-5
System Module
The following figure gives an example of IR transmission pulses. In IR transmission, a
light pulse corresponds to 0–bit and a "dark pulse" corresponds to 1–bit.
IR TX
UART TX
startbit
1
The FBUS cannot be used for external accessory communication, when the infrared mode
is selected. Infrared communication reserves the FBUS completely.

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 implemented 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 for
approximately ten minutes. If the backup has expired, the RTC clock restarts after the
main battery is connected. The CCONT resets the MCU in approx 62ms and the 32kHz
source is settled (after approx. 1s).
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
always running when the phone battery is connected. This sleep clock is used for a time
source to a RTC block.

Baseband Module

Technical Summary

The baseband architecture is basically similar to DCT3 GSM phones. DCT3.5 differs from
DCT3 in the single PCB concept and the serial interface between MAD2WD1 and
COBBA_GJP and MAD2WD1 and CCONT. In DCT3.5 the MCU, the system-specific ASIC
and the DSP are intergrated into one ASIC, called the MAD2WD1 chip, which takes care
of all the signal processing and operation controlling tasks of the phone.
The baseband architecture supports a power saving function called "sleep mode". This
sleep mode shuts off the VCTCXO, which is used as system clock source for both RF and
baseband. During the sleep mode the system runs from a 32 kHz crystal. The phone is
wakened up by a timer running from this 32 kHz clock supply. The sleeping time is deter-
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constant pulse
0 1 0 0

Figure 6: IR tramsmission frame - example

Nokia Mobile Phones Ltd.
PAMS Technical Documentation
1 1 0 stopbit
Issue 1 03/01