Microcontroller - Tait T880 II Series Adjustment Manual

M880-00
2.9

Microcontroller

(Refer to the microcontroller circuit diagram (sheet 8) in Section 6.2.)
12.8MHz
Clock
External
Serial Converter
Port
Audio In
Speech
Overall system control of the T885 is accomplished by the use of a member of the 80C51
family of microcontrollers (IC810) which runs from internal ROM and RAM. Four ports
are available for input/output functions.
Non-volatile data storage is achieved by serial communication with a 16kBit EEPROM
(IC820). This serial bus is also used by the microcontroller to program the synthesiser
(IC740).
The main tasks of the microcontroller are as follows:
• program the synthesiser;
• interface with the PGM800Win programming software at 9600 baud via the
serial communication lines on D-range 1 (PL100) & D-range 2;
• monitor channel change inputs from D-range 2;
• generate timing waveforms for CTCSS detection;
• coordinate and implement timing control of the receiver;
• control the front panel "Supply" LED.
Copyright TEL
5V Digital Watchdog Timer
Regulator
5V Reset
Microcontroller
CTCSS
Decoder
Figure 2.5 T885 Microcontroller Block Diagram
T885 Circuit Operation
& LVI
Watchdog
Microcontroller Cavity
Channel
Select
Port
Auxiliary
Output
Port
EEPROM
B2.9
Synthesiser
10/07/00