Finite-State Machine

Finite-State Machine for Arduino

typedefstruct {Predicatepredicate;// Predicate Function Pointerid_tnextF;// Next State on FALSEid_tnextT;// Next State on TRUEProcessprocess;// Process Function PointerEventHandlereventHandler;// Event Handler Function Pointer}Transition;

Initial State

voidbegin(constid_tid);

objectName.begin(3);// FSM begins with Initial Transition Id 3

Predicate Function

typedefbool (*Predicate)(id_t);//  Predicate Function Pointer

boolPredicateFunction(id_tid);//  Predicate Function

boolPredicateFunction(id_tid) {// TODO: PREDICATE FUNCTIONreturnbutton[id].isPressed(); }

boolPredicateFunction(id_tid) {// TODO: PREDICATE FUNCTIONreturnarray[id]==10; }

Next State

Process Function

typedefvoid (*Process)(State);//  Process Function Pointer

typedefstruct {id_tid;// State idboolfirstScan;// First Scan when State Activated}State;

voidProcessFunction(Statestate);//  Process Function

voidMotorProcess(Statestate) {StatusStatestatus;if (state.firstScan) {Serial.println("Motor Status Function")  }if (motor[state.id].timerON) {if (motor[state.id].running) {status=RUNNING;    }else {status=FAULT;    }digitalWrite(motor[state.in].faultPin,status==FAULT);  }}

id_tid=finiteStateMachine.id;

Event Handler Function

typedefvoid (*EventHandler)(EventArgs);//  Event Handler Function Pointer

typedefstruct {id_tid;// State idEventsevent;// Event State}EventArgs;

enumEvents :int8_t {PROCESS,EXIT,ENTRY,};

voidEventHandlerFunction(EventArgse);//  Event Handler Function Pointer

voidOnEventChanged(EventArgse) {switch (e.event) {caseENTRY:digitalWrite(motor[state.in].output, true);break;caseEXIT:digitalWrite(motor[state.in].output, false);break;  }}

Example

Fan Control With A Thermostat

State Diagram

Wiring Diagram

State-Transition Table

State-Transition Table -> Transition Declaration

Transitiontransitions[]= {  {FanStartPredicate,0,1,StartFan},// State-0 - Current-State = 0, Next-State = 1  {FanStopPredicate,1,0,StopFan}// State-1 - Current-State = 1, Next-State = 0};

Sketch

#include"FiniteState.h"#definethermostatPin   A0#definestartStatusPin  5#definestopStatusPin   6uint8_tstatusPins[]= {stopStatusPin,startStatusPin};constuint8_tnumberOfStatus=sizeof(statusPins) /sizeof(uint8_t);voidStartFan(Statestate);voidStopFan(Statestate);boolFanStartPredicate(id_tstate);boolFanStopPredicate(id_tstate);Transitiontransitions[]= {  {FanStartPredicate,0,1,StartFan},// State-0 - Current-State = 0, Next-State = 1  {FanStopPredicate,1,0,StopFan}// State-1 - Current-State = 1, Next-State = 0};constuint8_tnumberOfTransitions=sizeof(transitions) /sizeof(Transition);FiniteStatefiniteStateMachine(transitions,numberOfTransitions);// Finite-State ObjectconstlongThermostatRead();voidFanControl(id_tid);longtemperature;voidsetup() {for (uint8_tindex=0;index<numberOfStatus;index++) {pinMode(statusPins[index],OUTPUT);digitalWrite(statusPins[index],LOW);  }finiteStateMachine.begin(0);// FSM begins with Initial Transition Id 0}voidloop() {finiteStateMachine.execute();// Execute the FSMtemperature=ThermostatRead();// Read temperature}boolFanStartPredicate(id_tstate) {returntemperature >=40;// Determine Fan Start Action}voidStartFan(Statestate) {FanControl(state.id);// Fan control output}boolFanStopPredicate(id_tstate) {returntemperature <=30;// Determine Fan Stop Action}voidStopFan(Statestate) {FanControl(state.id);// Fan control output}voidFanControl(id_tid) {for (uint8_tindex=0;index<numberOfStatus;index++) {boolvalue=index==id;digitalWrite(statusPins[index],value);// Update Status  }}constlongThermostatRead() {longvalue=analogRead(thermostatPin);// Read Pushbutton Valuereturnmap(value,0,1023,0,100);// Scaling temperature}

Traffic Light

State Diagram

Wiring Diagram

State-Transition Table

State-Transition Table -> Transition Declaration

Transitiontransitions[]= {  {DelayTimePredicate,0,1,nullptr,EventStates},// State-0 - Current-State = 0, Next-State = 1  {DelayTimePredicate,1,2,nullptr,EventStates},// State-1 - Current-State = 1, Next-State = 2  {DelayTimePredicate,2,0,nullptr,EventStates},// State-2 - Current-State = 2, Next-State = 0};

Sketch

#include"FiniteState.h"#defineredLightPin     5#defineyellowLightPin  4#definegreenLightPin   3uint8_tlightPins[]= {redLightPin,greenLightPin,yellowLightPin};// Define an array of light pins.constuint8_tnumberOfLights=sizeof(lightPins) /sizeof(uint8_t);// Calculate the number of lights.typedefstruct {unsigned longdelayTime;unsigned longstartTime;}Timer;TimerdelayTimes[]= {  {5000},// RED Delay Time 5 seconds  {10000},// GREEN Delay Time 10 seconds  {3000},// YELLOW Delay Time 3 seconds};boolDelayTimePredicate(id_tid);// Predicate FunctionvoidEventStates(EventArgse);// Event StateTransitiontransitions[]= {  {DelayTimePredicate,0,1,nullptr,EventStates},// State-0 - Current-State = 0, Next-State = 1  {DelayTimePredicate,1,2,nullptr,EventStates},// State-1 - Current-State = 1, Next-State = 2  {DelayTimePredicate,2,0,nullptr,EventStates},// State-2 - Current-State = 2, Next-State = 0};constuint8_tnumberOftransitions=sizeof(transitions) /sizeof(Transition);// Calculate the number of transitions.FiniteStatefiniteStateMachine(transitions,numberOftransitions);// Define Finite-State Objectvoidsetup() {for (uint8_tindex=0;index<numberOfLights;index++) {pinMode(lightPins[index],OUTPUT);// Set Pin ModedigitalWrite(lightPins[index],LOW);// Set Light with the LOW state.  }finiteStateMachine.begin(0);// FSM begins with Initial Transition Id 0}voidloop() {finiteStateMachine.execute();// Execute the FSM}boolDelayTimePredicate(id_tid) {return (millis()-delayTimes[id].startTime >=delayTimes[id].delayTime);// Determine Time Delay}voidEventStates(EventArgse) {switch (e.event) {caseENTRY:delayTimes[e.id].startTime=millis();// Reload start timedigitalWrite(lightPins[e.id],HIGH);// Set Light with the HIGH state.break;caseEXIT:digitalWrite(lightPins[e.id],LOW);// Set Light with the LOW state.break;  }}

Reference