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Traffic light controller (4/4, ROM-based)DescriptionYet another traffic light controller,
realized as a Moore-type state-machine.
This time, however, both the next-state encoding as well as the
output data are stored in a ROM
addressed by the current state (via the flipflop outputs)
and three switches that control the traffic light behaviour:
The bindkeys 'b', 'g', and 't' are used for the blink, long-green,
and long-red switches,
with 'r' and 'c' use for the nreset switch and the clock generator.
- Blink: Selects a blink-only mode.
- TG: Selects a longer green-phase (6 instead of 3 clocks)
- TR: Selects a longer red-phase (6 instead of 3 clocks)
Use edit-component command from the popup-menu
to open the memory editor and view the ROM contents.
Note that both the next-state output (four bits)
and the LED output values (three bits)
fit into one word of the 1Kx8 bit ROM.
Obviously, using a ROM of size 1Kx8 bits is wasteful,
a ROM of size 128x8 bit would have been sufficient to store
the traffic-light data in this example.
Run the applet | Run the editor (via Webstart)
Impressum | 24.11.06