Multitone FLA 872, Technical Manual

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TLA 852/FLA 872
TM1205 Issue 2 Page 3 - 8
Pin 9 (CLK0) provides clock pulses to operate the microprocessor while it is in
standby mode.
Pin 11 (AREA) goes high when a valid signal is received.
Pin 14 (SDI) receives program information from the microprocessor.
Pin 2 (BS2) controls the ‘fast charge’ operation of the FSK comparator in IC401.
3.3.3 Microprocessor
The microprocessor controls the functions of the unit. A 4.19MHz clock, controlled
by XL2, provides the basic timing for the system.
Data received from IC402 is processed by the microprocessor and stored in the
SRAM chip, IC4. The microprocessor then causes the selected Alert to operate and
sends the message to the LCD module for display. Outputs from pin 5 (LCD-CS),
pin 39 (AD17), pin 38 (AD16) and pin 60 (WR) control the transfer of data to the LCD
module on the databus. Outputs from pins 2 and 7 control the operation of the audio
alert and the vibrate motor.
IC3 also controls the internal functions of the system, displaying the symbols and
changing the modes when selected by the three buttons on the front of the unit.
3.3.4 EEPROM
The EEPROM (IC1) holds information applicable to the unit, such as: Serial Number;
RIC codes; Radio parameters. The information is sent to the microprocessor through
the serial data link, pins 62, 63 and 64.
3.3.5 SRAM
The SRAM (IC4) is a 256k device which can store up to 32k of 8-bit information.
Address lines AD00 through AD14 and control lines RAM-CE and WR from the
microprocessor, control the flow of data in and out of the device on the databus.
3.3.6 LCD Module
The LCD Module produces the required characters and the symbols for the integral
display. Address lines AD16 and AD17 and control lines LCD-CS and WR from the
microprocessor, control the flow of data to the device on the databus.