CGU 04i DESCRIPTION
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2.4. Description of CGU 04i components
2.4.1 GSM module
Cinterion module is used for GSM network wireless communication. It is integrated into
printed circuit board. FME antenna connector is accessible from the back panel. Release SIM
card reader is located on the front panel.
The MC39i module communicates in three GSM bands (900 MHz, 1800 MHz
and 1900 MHz). It can transmit in two „Time Slots“ and receive in four (GPRS multi-slot class
10 – maximum reception bit speed 85.6 kb/s). It supports CS-1, CS-2, CS-3 and CS-4
encryptions).
2.4.2 Control microprocessor
Thirty-two-bit microprocessor Freescale Coldfire with 64 kB SRAM backup memory,
512 kByte FLASH EEPROM memory and realtime circuit with reserve power supply makes
for the basis of CGU 04i control microprocessor. Software is based on realtime operating
system that processes simultaneous tasks. Thus parallel operation of all external interfaces
of the communication module is maintained.
The microprocessor is connected through serial interface to MC39i OEM module
and controls the communication via GSM-GPRS. Towards a user it is connected on serial
interfaces RS 232 (PORT1), and direct I/O signal processing circuits. The microprocessor
enables connection of up to two user devices through two interfaces. The second ports
are linked to RJ45 connectors marked PORT2. This interface may be RS232, RS422, RS485,
M-BUSD or CNT. All user interface signals are protected against overvoltage on the data
cable.
A device with different communication protocol can be connected to each interface.
The microprocessor may work as a protocol converter between separate serial user interfaces.
In case other than RS232 interface device needs to be connected, e.g. RS485/422,
it is possible to connect level converter to the serial port according to particular application.
The microprocessor can control such external converter.