Sierra 200 owner manual Program ROM, On-chip data Eeprom, On-chip RAM

Software Architecture and Theory of Operation

This section of the manual is for those people interested in learning about the internal organization and behavior of the control system firmware. It is not necessary to understand all these details but will give you an deeper understanding of how it all works.

All primary repeater control functions are executed by the processor on the CPU board. The processor on the Radio Control Board handles initialization of radio board hardware, such as gain control pots, and generation of radio specific tones (key up telemetry, CW ID, busy signal).

The software for the CPU board is compiled into a program with a name format of SRSCnnmms.hex. The main version number is nn. The minor version number is mm. During development of any minor version, different passes of the code are given a letter, s. The v0.90 beta code is designated, SRSC0090. The binary executable to be loaded into the CPU board processor is in the file srscnnmms.hex. The software for the Radio Control board follows a similar naming scheme, SRSRnnmms. The binary executable to be loaded into the Radio Control board processor is in the file srsrnnmms.hex.

The controller has many parameters defining its configuration and operating behavior. Most of these can be easily changed by the site manager. These parameters have hard coded default values which are chosen so that most of the parameter values will be satisfactory for site operation without any further configuration.

The CPU and Radio Control boards have several forms of memory. Flash PROM on the processor chip contains the executable program. The size of this memory is 128kB, 64kB, and 32kB for the 18F8722, 18F4620, and 18F452 processors, respectively. Data RAM on the processor chip is used for working variables, program stack, etc. The size of this memory is 3982B for the 18F8722 and 18F4620, and 1536B for the 18F452. There is a nonvolatile data EEPROM on the processor chip. It is 1kB on the 18F8722 and 18F4620. Finally, there is an external serial EEPROM on the CPU board which is used to store configuration parameters. The size of this memory is 64kB, and the board has provisions for adding a second chip to double the memory. The hardware supports changing the contents of all of these forms of memory under program control.

Memory usage for the CPU board

Program ROM

Executable code, library of sound sequences, command table

On-chip data EEPROM

Reset counters

On-chip RAM

Working values of configuration parameters, program working variables, stack, etc.

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