Multitone RPR 583, Technical Manual

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RPR 583
TM1212 Issue 1 Page 3 - 8
3.3.3 Microprocessor
The microprocessor controls the functions of the unit. A 4.19MHz clock controlled
by XL1, provides the basic timing for the system.
A second clock (TR5, TR7, XL2) provides pulses at 32.768kHz, to operate the
microprocessor while it is in standby mode.
Data received from IC401 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. Outputs from pins 2, 7 and 8 control the operation of the audio alert,
the vibrate motor and the display backlight lamps.
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.
Putting the unit in the rack also connects the microprocessor’s PGM input (pin1) to
the paging system controller through the PROG contact at the rear of the unit. This
allows communication between the unit and the system controller.
3.3.4 EEPROM
The EEPROM (IC1) holds information applicable to the unit, such as: Serial Number;
RIC codes; Radio parameters; Programmed options. 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 256 k device which can store up to 32 k 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.
3.3.6 LCD Module
The LCD Module is a single device which contains all the necessary circuits to
produce the alpha-numeric 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.
C20 and C21 (pins 27 through 30) are part of the internal DC/DC converter of the
module’s negative bias supply.
R11, R12, R13, C17 and C22 through C25 are part of the circuit which controls the
voltage to the LCD driver.