User manual

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5.1.5 Central Processing Unit (CPU)
A tune-up algorithm implements antenna matching. It is designed
using the MC68HC711E9 microprocessor that features a versatile
instruction set, RAM, and EEPROM (memory which is saved after
the coupler is turned off).
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The antenna coupler relays are controlled by latches U6 and U7,
which receive serial data input directly from the CPU, and Q5.
During operation, data is transferred into the CPU from the A to D
ports and the Input Capture port (measures RF frequency).
The program monitors the status of the input sensors and—starting
from a preset condition—uses a built-in algorithm to achieve a
tuned condition. When the tuning algorithm is complete, the CPU
saves the settings in its EEPROM, which is addressed by the
applied RF frequency. This non-volatile memory table is the basis
of the exclusive learning feature of the MAC-200.
After it has stored and latched the network status, the CPU waits
for RF to cease transmitting and returns to the Stop mode. When
RF is re-transmitted, the first step in the tuning algorithm is to
measure the frequency of the signal passing through the coupler.
From the frequency data, the computer then searches its EEPROM
for previously stored data. If data is found, it is tested for validity,
and the required “end of tune” conditions will be sensed by the RF
sensors. Then the data will be latched in place, and the CPU will
again wait for RF to cease transmitting and turn to the Stop mode.
This process takes about 10 milliseconds, which is the same length
of time that is required to close the network relays.
5.1.6 Initialization