The objective of this assignment is to design and implement a circuit for controlling traffic
lights at the junction of two main roads. The procedure is as follows:
1. The circuit has control over a North-South road and an East-West road.
2. The North-South lights are controlled by outputs called nsr, nsy, and nsg (NorthSouth red, yellow, green).
3. The East-West road is controlled by similar outputs called ewr, ewy, ewg.
4. The cycle is controlled by an input called TIMER which controls the length of the two
greenlight cycles (s0 represents the EW green; s2 represents the NS green.)
5. When TIMER = 3, a transition from s0 to s1 or from s2 to s3 is possible. This
accompanies a change from green to yellow on the active road. The light on the
other road stays red.
6. An unconditional transition follows, changing the yellow light to red on one road and
the red light to green on the other.
7. The cycle can be set to any length by changing the signal on the TIMER input.
GREEN and RED are determined as follows:
– GREEN: sum of the last two digits of your student number PLUS 3
– RED: GREEN +3, so YELLOW is 3.
Example: your student ID 300582862, GREEN is 6+2+3=11 clock pulses, RED is
11+3=14 clock pulses. This can be generated by a mod-RED counter.
8. Note: GREEN+YELLOW in one direction = RED in another direction and vice versa!
9. The clock divider brings the on-board oscillator frequency down to the range of
visible observation for our CPLD board.
Attachments:
Project-M20.pdf
