TC-508 Service Manual
16
Figure 5
1) MCU Control Circuit
MCU control circuit is composed of MCU, EEPROM, keys and etc. This section has the following
functions: to initialize data of the radio and save data to EEPROM; to detect battery voltage and signals
from external keys, LD and VOX, and to make response; to transmit required data to PLL based on the
channel encoding status; to switch and control RX/TX based on the input PTT signal; to switch the
squelch circuit on/off based on the input signaling decode signal and squelch level signal; to control
circuits of high/low power switch, audio power amplifier, VCO power supply, RX power supply and TX
power supply; (for programming) to communicate with PC via RXD/TXD based on the RS232 protocol,
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