Hello Everyone,
First off, a huge thanks to Alto777 and L8R for their invaluable feedback on my previous sketch and for guiding me on improving my code. Your input has been incredibly helpful!
I’m still relatively new to C++ and Arduino programming, and I’m currently working on developing a finite state machine (FSM)-based vending self-service car wash machine. The goal is to create a system capable of dispensing water and foam within specified time intervals, with a play/pause feature for enhanced user control. Assuming that I’m on the right track, I’d love some feedback on my approach to further improve my sketch and ensure the design is efficient and error-free. I have yet to incorporate the ezButton library into my sketch.
I've replaced the universal coin slot temporarily with buttons with pull-down resistors;
Orange wire button = Add 1 to the balance,
Yellow wire button = Add 5 to the balance,
Green wire button = Add 10 to the balance,
Blue wire button = Pump water with play/pause feature,
Purple wire button = Pump foam with play/pause feature;
In summary, I am trying to use Arduino Uno R3 to control an electrical outlet operating at 220V which a pressure washer would be plugged in and solenoid valve/s via a relay module.
This is the reference of what I am trying to do:
https://youtu.be/9qqWdO3FCd4?si=3Ye_tw3Ca87vhiYM
Please note that there may still be some bugs that I haven’t discovered and fixed. Furthermore, I am currently doing this project in WOKWI simulation only and I have yet to proceed in building the actual hardware system. I am afraid of burning Arduino Uno R3 and relay modules if I proceed without caution and proper knowledge.
Looking forward to your insights!
This is my FMS Diagram:
This is my circuit diagram and Wokwi project link:
https://wokwi.com/projects/418858256122530817
This is my sketch:
// C++ code
# include <LiquidCrystal_I2C.h>
# define I2C_ADDR 0x27
# define LCD_COLUMNS 16
# define LCD_LINES 2
int balance = 0;
const int cost = 5;
// Pin for relay, to be connected to solenoid valve and solid state relay?
int relayPin_Motor = 9;
int relayPin_SolenoidValve = 10;
// Event flag for water and foam feature
bool isWatering = false;
bool isFoaming = false;
bool hasWaterTime = false;
bool hasFoamTime = false;
// Variables for toggle
int buttonState;
int prevButtonState = 0;
byte buttonPins[5] = {2, 3, 4, 5, 6};
byte buttonStates[5];
byte prevButtonStates[5] = {0, 0, 0, 0, 0};
unsigned long debounceStart[5] = {0, 0, 0, 0, 0};
const unsigned long debounceDelay = 50;
// Millis() variables
unsigned long currentMillis;
unsigned long startWaterMillis;
unsigned long startFoamMillis;
const unsigned long second = 1000UL;
const unsigned long minute = second * 60;
const unsigned long waterTime = minute / 5;
const unsigned long foamTime = minute / 5;
unsigned long elapsedWaterTime;
unsigned long elapsedFoamTime;
unsigned long waterTimeLeft = 0;
unsigned long foamTimeLeft = 0;
long displayWaterTime = 0;
long displayFoamTime = 0;
// Enum variable for the machine state
enum MachineState {IDLE, SELECTION, WATER, FOAM};
MachineState state;
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);
void setup()
{
// Serial
Serial.begin(115200);
//Intialize the LCD
lcd.init();
//Set the pin of coinButtons
// Set the pin of water and foam button
for(int buttonPin: buttonPins)
{
pinMode(buttonPin, INPUT);
}
// Set the pin of relay
pinMode(relayPin_Motor, OUTPUT);
pinMode(relayPin_SolenoidValve, OUTPUT);
// Set the default state of the machine
state = IDLE;
}
void loop()
{
currentMillis = millis();
ReadDebounceButton();
HandleMachineState();
}
// Handle the states and transitions of the machine
void HandleMachineState()
{
switch(state)
{
case IDLE:
// Transition to SELECTION state if balance is greater than or equal to the cost of water or foam
if(balance >= cost)
{
state = SELECTION;
}
else if(balance < cost)
{
if(hasWaterTime || hasFoamTime)
{
// Transition to SELECTION state if either water or foam has time left
state = SELECTION;
}
else
{
// Display insert coins instruction
// Display the current balance
DisplayInsert();
DisplayBalance(balance);
}
}
break;
case SELECTION:
// Display press a button instruction
// Display the current balance
if(!hasWaterTime && !hasFoamTime)
{
DisplayPress();
DisplayBalance(balance);
}
else
{
// Display the time left of the water and foam if either has any
// Display the current balance
DisplayMinSec(0, 0, "WTR", displayWaterTime);
DisplayMinSec(9, 0, "FM", displayFoamTime);
DisplayBalance(balance);
}
break;
// If condition?
case WATER:
PumpWater();
DisplayBalance(balance);
break;
case FOAM:
PumpFoam();
DisplayBalance(balance);
break;
}
}
// Read and debounce the water button
// TO-DO: Convert this method to be reused with different buttons in the circuit
// As buttons results to different output, converting this to reusable debounce button method is a challenge
// Abstract the switch case for different outputs?
void ReadDebounceButton(){
for(int currentButton = 0; currentButton < sizeof(buttonPins); currentButton++)
{
int reading = digitalRead(buttonPins[currentButton]);
if (reading != prevButtonStates[currentButton]) {
debounceStart[currentButton] = currentMillis;
}
if ((currentMillis - debounceStart[currentButton]) > debounceDelay) {
if (reading != buttonStates[currentButton]) {
buttonStates[currentButton] = reading;
if (buttonStates[currentButton] == 1) {
lcd.clear();
switch(buttonPins[currentButton])
{
case 2:
Serial.println(F("1-peso Button Pressed"));
balance += 1;
break;
case 3:
Serial.println(F("5-pesos Button Pressed"));
balance += 5;
break;
case 4:
Serial.println(F("10-pesos Button Pressed"));
balance += 10;
break;
case 5:
Serial.println(F("Water Button Pressed"));
WaterButtonOutputs();
break;
case 6:
Serial.println(F("Foam Button Pressed"));
FoamButtonOutputs();
break;
default:
Serial.println(F("No button was read"));
}
}
}
}
prevButtonStates[currentButton] = reading;
}
}
// Handles the diffrent outputs of pressed water button based on the current state of the machine
void WaterButtonOutputs()
{
switch(state)
{
case IDLE:
DisplayInsufficient();
// TO-DO: Search for better solution instead of using delay in lcd displa, use millis() instead?
delay(second / 2);
break;
case SELECTION:
if(balance >= cost)
{
if(!hasWaterTime)
{
balance -= cost;
waterTimeLeft = waterTime;
startWaterMillis = currentMillis;
isWatering = true;
hasWaterTime = true;
state = WATER;
}
}
else if(balance < cost)
{
if(hasWaterTime)
{
TogglePumpWater();
state = WATER;
}
else
{
DisplayInsufficient();
delay(second / 2);
lcd.clear();
}
}
break;
case WATER:
TogglePumpWater();
PumpWater(); // Call the PumpWater again to turn off the relay before transitioning to SELECTION state
state = SELECTION;
break;
case FOAM:
TogglePumpFoam();
PumpFoam(); // Call the PumpFoam again to turn off the relay before transitioning to WATER state
if(balance >= cost)
{
if(!hasWaterTime)
{
balance -= cost;
waterTimeLeft = waterTime;
startWaterMillis = currentMillis;
isWatering = true;
hasWaterTime = true;
state = WATER;
}
}
else if(balance < cost)
{
if(hasWaterTime)
{
TogglePumpWater();
state = WATER;
}
else
{
DisplayInsufficient();
delay(second / 2);
lcd.clear();
state = IDLE;
}
}
break;
default:
state = IDLE;
}
}
// Handles the diffrent outputs of pressed foam button based on the current state of the machine
void FoamButtonOutputs()
{
switch(state)
{
case IDLE:
DisplayInsufficient();
// TO-DO: Search for better solution instead of using delay in lcd displa, use millis() instead?
delay(second);
break;
case SELECTION:
if(balance >= cost)
{
if(!hasFoamTime)
{
balance -= cost;
foamTimeLeft = foamTime;
startFoamMillis = currentMillis;
isFoaming = true;
hasFoamTime = true;
state = FOAM;
}
}
else if(balance < cost)
{
if(hasFoamTime)
{
TogglePumpFoam();
state = FOAM;
}
else
{
DisplayInsufficient();
delay(second / 2);
lcd.clear();
}
}
break;
case WATER:
TogglePumpWater();
PumpWater(); // Call the PumpWater again to turn off the relay before transitioning to FOAM state
if(balance >= cost)
{
if(!hasFoamTime)
{
balance -= cost;
foamTimeLeft = foamTime;
startFoamMillis = currentMillis;
isFoaming = true;
hasFoamTime = true;
state = FOAM;
}
}
else if(balance < cost)
{
if(hasFoamTime)
{
TogglePumpFoam();
state = FOAM;
}
else
{
DisplayInsufficient();
delay(second / 2);
lcd.clear();
state = IDLE;
}
}
break;
case FOAM:
TogglePumpFoam();
PumpFoam(); // Call the PumpFoam again to turn off the relay before transitioning to SELECTION state
state = SELECTION;
break;
default:
state = IDLE;
}
}
// Method to pump water
void PumpWater()
{
// long displayWaterTime; Global variable?
if(isWatering)
{
elapsedWaterTime = currentMillis - startWaterMillis;
if(elapsedWaterTime > waterTimeLeft)
{
// Turn off the relay
if(digitalRead(relayPin_Motor) == 1)
{
digitalWrite(relayPin_Motor, 0);
}
// Reset the water event flags
// Transition to the IDLE state after the countdown
isWatering = false;
hasWaterTime = false;
}
else if(elapsedWaterTime <= waterTimeLeft)
{
// Turn on the relay
if(digitalRead(relayPin_Motor) == 0)
{
digitalWrite(relayPin_Motor, 1);
}
displayWaterTime = waterTimeLeft - elapsedWaterTime;
}
}
else if(!isWatering)
{
// This condition could not be read as the state transition to another state.
// Problem: Could not turn off the relay during paused countdown.
// Solution? Also call the PumpWater in selection state or after toggling? Split the pumpwater into on and off of water pump?
// Turn off the relay
if(digitalRead(relayPin_Motor) == 1)
{
digitalWrite(relayPin_Motor, 0);
}
// Update the displayWaterTime based on waterTimeLeft;
if(hasWaterTime)
{
displayWaterTime = waterTimeLeft;
}
}
// Display water time left
// Display the foam time as well?
if(hasWaterTime)
{
DisplayMinSec(0, 0, "WTR", displayWaterTime);
DisplayMinSec(9, 0, "FM", displayFoamTime);
}
else if(!hasWaterTime)
{
// Reset the waterTimeLeft and displayWaterTime after the countdown
waterTimeLeft = 0;
displayWaterTime = 0;
state = IDLE;
}
}
// Play/Pause toggle of the pump water and water time countdown:
void TogglePumpWater()
{
isWatering = !isWatering;
if(isWatering)
{
// Update the start millis of water countdown
startWaterMillis = currentMillis;
Serial.println(F("WATER IS RUNNING"));
}
else if(!isWatering)
{
// Update the water time left
waterTimeLeft -= elapsedWaterTime;
Serial.println(F("WATER HAS STOPPED"));
}
}
// Method to pump foam
void PumpFoam()
{
// long displayFoamTime; Global variable?
if(isFoaming)
{
elapsedFoamTime = currentMillis - startFoamMillis;
if(elapsedFoamTime > foamTimeLeft)
{
// Turn off the relay
if(digitalRead(relayPin_SolenoidValve) == 1)
{
digitalWrite(relayPin_SolenoidValve, 0);
}
// Reset the water event flags
// Transition to the IDLE state after the countdown
isFoaming = false;
hasFoamTime = false;
}
else if(elapsedFoamTime <= foamTimeLeft)
{
// Turn on the relay
if(digitalRead(relayPin_SolenoidValve) == 0)
{
digitalWrite(relayPin_SolenoidValve, 1);
}
displayFoamTime = foamTimeLeft - elapsedFoamTime;
}
}
else if(!isFoaming)
{
// This condition could not be read as the state transition to another state.
// Problem: Could not turn off the relay during paused countdown.
// Solution? Also call the PumpFoam in selection state or after toggling? Split the pump foam into on and off of foam pump?
// Turn off the relay
if(digitalRead(relayPin_SolenoidValve) == 1)
{
digitalWrite(relayPin_SolenoidValve, 0);
}
// Update the displayFoamTime based on foamTimeLeft;
if(hasFoamTime)
{
displayFoamTime = foamTimeLeft;
}
}
// Display water time left
// Display the foam time as well?
if(hasFoamTime)
{
DisplayMinSec(0, 0, "WTR", displayWaterTime);
DisplayMinSec(9, 0, "FM", displayFoamTime);
}
else if(!hasFoamTime)
{
// Reset the waterTimeLeft and displayWaterTime after the countdown
foamTimeLeft = 0;
displayFoamTime = 0;
state = IDLE;
}
}
// Play/Pause toggle of the pump foam and foam time countdown:
void TogglePumpFoam()
{
isFoaming = !isFoaming;
if(isFoaming)
{
// Update the start millis of water countdown
startFoamMillis = currentMillis;
Serial.println(F("FOAM IS RUNNING"));
}
else if(!isFoaming)
{
// Update the water time left
foamTimeLeft -= elapsedFoamTime;
Serial.println(F("FOAM HAS STOPPED"));
}
}
// Display the milliseconds in minutes:seconds format
void DisplayMinSec(int h, int v, String s, long time)
{
lcd.setCursor(h, v);
lcd.print(s);
int countdown_minute = ((time / 1000) / 60) % 60;
int countdown_sec = (time / 1000) % 60;
if(countdown_minute < 10)
{
lcd.print(' ');
}
lcd.print(countdown_minute);
lcd.print(':');
if(countdown_sec < 10)
{
lcd.print('0');
}
lcd.print(countdown_sec);
}
// Display the current balance, parameter?
void DisplayBalance(int bal)
{
lcd.setCursor(0, 1);
lcd.print(" BALANCE: P");
lcd.print(bal);
}
// Display the coin insert instruction
void DisplayInsert()
{
lcd.home();
lcd.print("INSERT:P1,P5,P10");
}
// Display the press a button instruction
void DisplayPress()
{
lcd.home();
lcd.print(" PRESS A BUTTON ");
}
// Display the insufficient balance instruction
void DisplayInsufficient()
{
lcd.home();
lcd.print(" INSUFF BALANCE ");
}Thank you very much in advance!