Internal Ports; Modem; Baud Clock; I2C Controller - Ericsson EF738 Service Manual

Technical Description

Internal Ports

There are three 8 bit read and three 8 bit write ports in this block that are used within
GUSTAV.

Modem

The modem part supports two different cellular systems, AMPS and TACS, which
consists of data receiver, data transmitter, SAT detector, and SAT transmitter.
The data receiver consists of three parts: digital discriminator, data decoder, and
wordsync detector.
The data transmitter sends data bytewise where the most significant bit is transmit-
ted first.
The SAT-detection consists of continuous measurements of 10-12 ms and the three
frequencies being used are 5970, 6000 and 6030 Hz.
SAT-generation of the three frequencies is also done in GUSTAV.

Baud Clock

This block generates the baud rate for the serial interface of GUSTAV and is select-
able among the following baud rates.
600 (Power on default)
1200
2400
4800
9600

I2C Controller

This part controls the communication between the EEPROM and the display.

FLASH EPROM

The system program is stored in a low voltage Flash EPROM with 128k x 8 bit area.

EEPROM

The 'customer' PROM is a CMOS EEPROM with 4k x 8 bit area. Data that has to
be saved when the station is turned off is stored in this memory, which contains the
telephone number, short numbers, talk time, area ID and other radio/audio informa-
tion.
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