The Mux: Difference between revisions
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''The main mux'' is the huge black thing in the AV rack, it routes video to different places, and also has analogue TV demodulators in. The main mux is controlled by an outboard box which sits on the directors/vision mixers desk. | ''The main mux'' is the huge black thing in the AV rack, it routes video to different places, and also has analogue TV demodulators in. The main mux is controlled by an outboard box which sits on the directors/vision mixers desk. | ||
==Functions== | =='''Functions'''== | ||
* 32 input to 4 output matrix | * 32 input to 4 output matrix | ||
* 2 Nicam stereo tuners | * 2 Nicam stereo tuners | ||
==Faults== | =='''Faults'''== | ||
2 composite inputs to the matrix are dead. | 2 composite inputs to the matrix are dead. | ||
=== | =='''controller'''== | ||
==pinouts== | |||
'''1''' - +5V power | '''1''' - +5V power | ||
'''2''' - 0V ground | '''2''' - 0V ground | ||
'''3''' - | '''3''' - 32x4 crosspoint switch control lines | ||
'''4''' | '''4''' - consisting of a clock (rising edge trigger) | ||
'''5''' - | '''5''' - CS (active-low) and Data | ||
'''6''' - NC | '''6''' - NC | ||
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==explanation of operation== | ==explanation of operation== | ||
This was originally based around a PIC16F84 with an 8MHz crystal containing code written by Rob Sprowson. The hex file as loaded into the PIC can be found here[[https://ystv.york.ac.uk/~documents/docs_resources/StationDocumentation/muxController_sprow.hex]] whilst a partial disassembly of it can be found here [[https://ystv.york.ac.uk/~documents/docs_resources/StationDocumentation/muxController_sprow.doc]]. Also available is a disassembled version of the ROM code [[https://ystv.york.ac.uk/~documents/docs_resources/StationDocumentation/schedula_rom_disassembled.txt]] from within the BBC micro that used to be part of Schedula. | This was originally based around a PIC16F84 with an 8MHz crystal containing code written by Rob Sprowson. The hex file as loaded into the PIC can be found here[[https://ystv.york.ac.uk/~documents/docs_resources/StationDocumentation/muxController_sprow.hex]] whilst a partial disassembly of it can be found here [[https://ystv.york.ac.uk/~documents/docs_resources/StationDocumentation/muxController_sprow.doc]]. Also available is a disassembled version of the ROM code [[https://ystv.york.ac.uk/~documents/docs_resources/StationDocumentation/schedula_rom_disassembled.txt]] from within the BBC micro that used to be part of Schedula. | ||
A new PIC, a PIC18F2455 using a 20MHz crystal, has replaced this PIC through use of an extra 'daughter' board. This change in PIC was to allow easier coding, using C instead of assembler, and to provide USB capabilites. The source code can be found in [[Main Mux Source Code]]. | |||