Nokia NSE-3 SERIES, Руководство по обслуживанию

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PAMS
Technical Documentation
NSE–3
System Module
Page 3 – 45
Original 11/97
Infrared Transceiver Module
The module is activated with an IRON signal by the MAD, which supplies
power to the module. The IR datalines are connected to the MAD acces-
sory interface AccIf via FBUS. The RX and TX lines are separated from
FBUS by three–state buffers, when the IR–module is switched off. The
AccIf in MAD performs pulse encoding and shaping for transmitted data
and detection and decoding for received data pulses.
The data is transferred over the IR link using serial data at speeds 9.6,
19.2, 38.4, 57.6 or 115.2 kbits/s, which leads to maximum throughput of
92.160 kbits/s. The used IR module complies with the IrDA 1.0 specifica-
tion (Infra Red Data Association), which is based on the HP SIR (Hewlett–
Packard‘s Serial Infra Red) consept.
Following figure gives an example of IR transmission pulses. In IR transmission
a light pulse correspondes to 0–bit and a ”dark pulse” correspondes to 1–bit.
UART TX
IR TX
startbit stopbit
1
0 1 0 0 1 1 0
constant pulse
The FBUS cannot be used for external accessory communication when the in-
frared mode is selected, as IR 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 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.