C2.4 T854 Circuit Operation M8SL2-00-002-812
© Copyright Tait Electronics Limited August 2004. All rights reserved.
2.2 Microcontroller
Refer to the microcontroller circuit diagram (Sheet 8 – T854 Microcontroller) in Section
6.2
Figure 2.2 T854 Microcontroller Block Diagram
Overall system control of the T854 is accomplished by the use of a member of the 80C51
family of microcontrollers (IC810). It runs from internal ROM and RAM, thus leaving all
four ports free 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) and deviation control EPOTS (IC220).
The main tasks of the microcontroller are as follows:
• program the synthesiser and EPOT;
• interface with the PGM800Win programming software at 9600 baud via the
serial communication lines on D-range 1 (PL100) and D-range 2;
• monitor channel change inputs from D-range 2;
• generate timing waveforms for CTCSS encoding;
• coordinate and implement timing control of the transmitter.
• control the front panel “Supply” LED (refer to Section 5.3).
5V Reset
5V Digital
Regulator
Watchdog
Reset
Channel
Select
Port
Auxiliary
Output
Port
Microcontroller
12.8MHz
Clock
Microcontroller Cavity
CTCSS Tone
External
Serial
Port
EEPROM
Synthesiser
Dual Digital
Potentiometer
CTCSS
Encoder
Converter
To Next Page
Loading...
