Ok I am going review some of the RSS as it is changing but in a good way..
Figure 1. RSS Block Diagram |
The RSS_IOP has a lot of jobs (review):
- Physical radios themselves.
- The radio's interface system (arduino cards).
- Driving some intruments (flags, lights, etc)
- The interface to NavGroup intranet ( and decoding messages).
- Morse Code generator.
- FAA radio data base. (mySQL)
- Radio simulator.
- Line of sight calculations (between radios and aircraft)
- Crew audio station(s).
- Moving audio from different sources to the right audio line (LASA Patch Bay)
Currently we will only concern our selves with the radios functionality 1 and the interface system 2.
The radio model has been changed thankfully to a UML editor from Mentor Graphics.
The Analysis:
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Figure 2. RSS Radio Model |
We can look at a radio in three (3) parts;
- The physical radio (common to all radios). This is the structure referred to as radios[]. This is an array of all the radios.
- The interface. This is was makes each radio unique. This is the structure referred to as radio_XXXX.
- The tuner or tuners. The tuner is just that. It hold the tuned frequency, and its file descriptors. This is the structure referred to a tuner_XXXX.
Each one of the structures need a forward reference ie. a pointer to the next lower structure. So when we get a interrupt from one of the tuners, we can just grab the right tuner. But what if we have turn on/off in one of the upper structures? We added two (2) backwards references, or pointers in the tuner's structure.
The protocol between the interface card (arduino) and the RSS_IOP is as follows:
Between the arduino and the RSS_IOP: 3 bytes; 1 RADIO_ID, 2 SWITCH, 3 DATA. Then the RSS_IOP NAC's or ACC's back;
Between the RSS_IOP and the arduino; 3 bytes; 1 RADIO_ID, 2 OUTPUT, 3 DATA. Then the arduino NAC's or ACC's back;
Radio Head (Hardware):
Any radio head can be interfaced to the system, such as:
- ARINC-410: Decoding is done on the RSS_IOP
- ARINC-429: Separate interface card in the RSS_IOP
- MIL-1553: Separate interface card in the RSS_IOP
- Custom: You build it, well make it work
~~ Cris