Comtech EF Data SDM-100A - Manual (Page 127)

SDM-100A Satellite Modem Theory of Operation
Rev. 0 4–11
4.3 Monitor and Control
A sophisticated microcontroller module is used to perform the monitor and control
functions of the modem. This module is located on the demodulator board, and is referred
to as the Monitor and Control (M&C). The M&C monitors the modem, and provides
configuration updates to other modules within the modem when necessary.
Extensive fault monitoring and status gathering are provided.
Modem configuration parameters are maintained in battery-backed RAM, which provides
for total recovery after a power-down situation.
All modem functions are accessible through a local front panel interface and a remote
communications interface.
4.3.1 Non-Volatile Memory
Non-volatile memory on the M&C module allows it to retain configuration information
for at least one year without power.
Should the modem be powered down, the following sequence is carried out when power
is applied to the M&C:
1. The microcontroller checks the non-volatile memory RAM to see if valid data
has been retained. If valid data has been retained, the modem is reconfigured to
that configuration.
2. If non-volatile memory fails the valid data test, a default configuration from
ROM is loaded into the system.
4.3.2 M&C Theory of Operation
The M&C module is built around the Intel 80C32 microcontroller, which operates at
11.0592 MHz. The microsystem is designed to support up to 512 kbytes of read-only
code memory, and up to 32 kbytes of non-volatile random access data memory. The
80C32 microcontroller supports a serial asynchronous communications channel, with a
maximum data rate of 19.2 kbit/s.
4.3.3 Remote Interface Specification
Refer to Appendix A.