Motion-activated traffic signal

For our extra credit project we designed a functioning traffic signal. The traffic light contains a red, yellow and green LED; which are controlled by a PIR Motion Sensor (passive infrared. The PIC24 has internal pull-ups (0 = true), while the PIR sensor sends a (1= true) value when motion is sensed. To accommodate the logic difference, we incorporated a 2N3904 transistor as a switch to reverse the logic sent to the PIC24. The designed traffic light can be implemented with other traffic lights to build a full working intersection.

Schematic:

Grading: 20 points

1. Scope -- reasonable; a digital PIR sensor plus LEDs
2. Functionality -- good
3. Hardware complexity - good; use of a transistor added some complexity
4. Software complexity - low
5. Presentation - N/A
6. Practicality / usefulness / fun factor - good; nice addition to allow cars to run the red light without restarting the cycle.