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When the train crosses the small isolated piece of track, a low is presented to the GP3 port of the PIC. The Red or Yellow inputs are sensed on GP4 and 5. The program is continually checking these inputs and will set the aspects accordingly. Red over-rides Yellow and Green is set if the others are not. When a spot has been crossed then a delay is started and Red set.
At the end of this delay the Yellow is set and its delay started. At the end of this the signals revert to Green. A Red or Yellow input will clear the delay timers. If the track power is reversed it will force Red as the train direction is opposing the signal. The Red Out will be wired to the preceeding signals Yellow input to set it to caution from an up-track red.
When the train crosses the small isolated piece of track, a low is presented to the GP3 port of the PIC. The Red or Yellow inputs are sensed on GP4 and 5. The program is continually checking these inputs and will set the aspects accordingly. Red over-rides Yellow and Green is set if the others are not. When a spot has been crossed then a delay is started and Red set.
At the end of this delay the Yellow is set and its delay started. At the end of this the signals revert to Green. A Red or Yellow input will clear the delay timers. If the track power is reversed it will force Red as the train direction is opposing the signal. The Red Out will be wired to the preceeding signals Yellow input to set it to caution from an up-track red.
LINK TO IMAGE - pic12-1.gif
Circuit Schematic
