Finite state machine code sample for a traffic light system with pedestrian call buttom, alert and off states.

Made for ST STM32F4 Discovery board using ARM Mbed library and PlatformIO IoT Ecosystem.

Challenge for students of the discipline Microprocessed Systems II at SENAI CIMATEC university center.

Keywords: Traffic light, Finite State Machine, C/C++, Mbed, STM32F4

Finite State Machine policy

• States: Red; Green; Yellow; Alert (Only Yellow blinking at 1Hz); Off.
• Initial state: Red
• Transition Red -> Green: t=10s
• Transition - Green --> Yellow: t=20s || tBt=<3s
• Transition - Yellow --> Red: t=4s
• Transition - Any other state --> Alert: tBt>=3s && tBt<=10s
• Transition - Any other state --> Off: tBt>10s
• Transition - Off -- > Red: tBt > 10s
• Transition - Alert --> Previous state: tBt>=3s && tBt<=10s
• t = elapsed time; tBt = time Button pressed.