DESCRIPTION AND OPERATION
MODULE CIRCUITRY
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I-E96-302B
®
The microprocessor directs and coordinates the operation of
the functional blocks that make up the FBS module. The mod-
ule stores (in memory) the transmitter configurations it
receives from the controlling module during start-up. The
microprocessor uses this information to monitor transmitter
status. The FBS module can initiate action to correct nonfatal
errors it detects during normal operation such as a communi-
cation error from a transmitter.
The microprocessor selects an individual input channel
through a multiplexing scheme. There are several sets of multi-
plexers that handle the various inputs for each mode of opera-
tion. On-board jumpers set the module operating mode (define
the type of input). Thus, when an input type is selected, the
microprocessor directs all inputs to the proper conversion or
decoding circuitry. Inputs pass through analog-to-digital con-
version if they are analog inputs or through FSK decoding if
they are digital. On-board jumpers also set the communication
mode (FSK or baseband). The microprocessor directs commu-
nication by multiplexing the signals to the proper communica-
tion circuitry for decoding (or encoding).
A dual slope analog-to-digital converter (ADC) handles conver-
sion of analog inputs. It has 14-bit resolution and polarity
detection. An analog-to-digital control chip contains logic that
the microprocessor uses to control the ADC circuitry. The FBS
module stores the data it receives from the ADC circuitry in
memory. When the controlling module requests process data
from a particular input channel, the FBS module sends it the
most current data that it has in memory.
MODULE CIRCUITRY
The following sections explain the operation of the five func-
tional blocks that make up the FBS circuitry.
Microprocessor and Control Logic
The on-board microprocessor and control logic coordinates
module functions. The microprocessor has four main
functions:
•
Storing the digital data in random access memory (RAM).
•
Coordinating analog-to-digital conversion through the ana-
log-to-digital control chip.
•
Preparing digital commands to send to the smart
transmitters.
