This simple project controls a single UK road traffic light, and stops the traffic whenever a pedestrian wants to cross the road.
The electronics consist of three LEDs (red, yellow and green) which are connected to the digital pins D1, D2 and D3 via current limiting resistors. The pedestrian crossing input is a single button connected between 3v and D4.
The pictures below shows the device in action.
And a nice little GIF of it in action…
The program shows the green light and waits in a loop until the pedestrian crossing button is pushed. It then shows the amber light for 3 seconds, then the red light for three seconds. After that the amber comes on also for a further three seconds, and then switches back to a green light.
10 REM TRAFFIC LIGHTS 20 REM SETUP PINS 30 SYS 10,1,1:SYS 10,2,1:SYS 10,3,1:SYS 10,4,0 100 REM START ON GREEN 110 GOSUB 1200 115 REM WAIT FOR THE CROSS ROAD BUTTON 120 REPEAT 121 UNTIL SYS(12,4)=1 130 GOSUB 1300 140 WAIT(3000) 150 GOSUB 1000 160 WAIT(3000) 170 GOSUB 1100 180 WAIT(3000) 190 GOTO 110 1000 REM RED LIGHT 1010 SYS 11,1,1:SYS 11,2,0:SYS 11,3,0 1020 RETURN 1100 REM RED-AMBER 1110 SYS 11,1,1:SYS 11,2,1:SYS 11,3,0 1120 RETURN 1200 REM GREEN 1210 SYS 11,1,0:SYS 11,2,0:SYS 11,3,1 1220 RETURN 1300 REM AMBER LIGHT 1310 SYS 11,1,0:SYS 11,2,1:SYS 11,3,0 1320 RETURN
