Fixing a pedestrian traffic light sequence pattern in a cycle using millis and without delay

Question

I was emulating the pedestrian traffic light cyclic pattern (red, green, green flashing) in the next Arduino code. But when I run this code with my ESP8266 Wemos D1 mini controller, it appears the pattern (red, red and (green flashing) at the same time, green). I do not know why this strange pattern appeared and I was trying to fix it, but I did not get anything. How to fix this code to replicate the (red, green, green flashing) sequence pattern?

// Define pin assignments
const int redLED = D1;
const int greenLED = D2;
const int pedestrianButton = D3;
const int potentiometer = A0;
// Define variables
unsigned long lastStateChangeTime = 0;
unsigned long greenFlashingDuration = 3000; // 3 seconds
unsigned long redGreenDuration = 5000; // Initial duration
bool pedestrianRequest = false;
void setup() {
 // Initialize pins
 pinMode(greenLED, OUTPUT);
 pinMode(redLED, OUTPUT);
 pinMode(pedestrianButton, INPUT_PULLUP);
 attachInterrupt(digitalPinToInterrupt(pedestrianButton), pedestrianInterrupt, FALLING);
}
void loop() {
 updateTiming(); // Read potentiometer/LDR and update timings
 manageTrafficLights(); // Manage traffic light states
}
void manageTrafficLights() {
 unsigned long currentTime = millis();
 if (pedestrianRequest==true) {
 // Pedestrian request prioritized
 digitalWrite(greenLED, HIGH);
 digitalWrite(redLED, LOW);
 
 pedestrianRequest = false;
 }
 
 // Determine the state based on the timing
 
 if ( (currentTime-lastStateChangeTime) >= (2 * redGreenDuration) ) {
 lastStateChangeTime = currentTime; // Reset cycle
 }
 else {
 if ( (currentTime-lastStateChangeTime) < redGreenDuration ) {
 digitalWrite(greenLED, LOW);
 digitalWrite(redLED, HIGH); // Red state
 } else if ( (currentTime-lastStateChangeTime) < (2*redGreenDuration-greenFlashingDuration) ) {
 digitalWrite(redLED, LOW);
 digitalWrite(greenLED, HIGH); // Green state
 } else {
 digitalWrite(redLED, LOW);
 
 if ( ( (currentTime-lastStateChangeTime) >= (2*redGreenDuration-greenFlashingDuration) ) 
 && ( (currentTime-lastStateChangeTime) % (greenFlashingDuration/3) < (greenFlashingDuration/6) ) ){
 digitalWrite(greenLED, LOW);
 } else {
 digitalWrite(greenLED, HIGH);
 }
 
 }
 }
 
}
void updateTiming() {
 // Read potentiometer/LDR values and map to timings
 // Update redGreenDuration and greenFlashingDuration accordingly
 redGreenDuration = map(analogRead(potentiometer), 0, 1023, 5000, 10000);
}
void pedestrianInterrupt() {
 pedestrianRequest = true;
 // Quickly change to green if in red state
 if (digitalRead(redLED) == HIGH) {
 digitalWrite(greenLED, HIGH);
 digitalWrite(redLED, LOW);
 lastStateChangeTime = millis(); // Reset the cycle
 }
 
}

Answer 1

Here is some simplified example code that might be useful to you.

It keeps the logic and the LED control separated by the use of flags.

Simulation is at https://wokwi.com/projects/389132610627050497

// https://arduino.stackexchange.com/questions/95476/fixing-a-pedestrian-traffic-light-sequence-pattern-in-a-cycle-using-millis-and-w
// for simulation, see https://wokwi.com/projects/389127817478781953
const int redLED = 2;
const int greenLED = 3;
unsigned int timeInterval [4] = { 5, 3, 4, 0}; // timers reload with these values
unsigned int timeCounter [4] = { 0, 0, 0, 0}; // these are the actual timers
//boolean reloadable [4] = {true, true, false, false}; // this determines if the timer will restart upon reaching end
 // put value in <timeCounter> for oneshot event 
 // 3rd and 4th timers are not used in this example sketch
boolean tick [4] = {false, false, false, false}; // countdown timers flags
boolean mainTick = false;
boolean subTick = false;
boolean red = false;
boolean green = false;
boolean blink = false;
unsigned long previousMillis = 0;
void setup() {
 Serial.begin(115200);
//memcpy(timeCounter, timeInterval, 4 * sizeof(long)); // preload timers
 green = true; // start with green
 timeCounter[0] = 1; // load the first counter
}
void loop() {
 unsigned long currentMillis = millis();
// -------------------------------------------------------------------
 if (currentMillis - previousMillis >= 500) { // 0.5 s tick
 previousMillis = currentMillis;
 subTick = !subTick; // alternate the value
 if (subTick) {
 mainTick = true; // 1 s tick
 // Serial.println("tick"); // debugging code
 for (int i = 0; i < 4; i++) { // keep track of 4 time intervals
 timeCounter[i]-- ; // decrement counter
 if (timeCounter[i] == 0) {
 // if (reloadable[i]) timeCounter[i] = timeInterval[i]; // reached zero, reload counter if it is reloadable
 tick[i] = true; // emit a "tick"
 }
 }
 }
 }
// -------------------------------------------------------------------
 if (mainTick) { // 1 s tick
 }
// -------------------------------------------------------------------
 if (tick[0]) { //
 tick[0] = false;
 timeCounter[1] = timeInterval[1]; // setup the next tick
 red = false; // setup flags
 green = true;
 blink = false;
 }
// -------------------------------------------------------------------
 if (tick[1]) { //
 tick[1] = false; // clear flag so that code runs only once every tick
 timeCounter[2] = timeInterval[2]; // setup the next tick
 red = true;
 green = false;
 blink = false;
 }
// -------------------------------------------------------------------
 if (tick[2]) { //
 tick[2] = false; // clear flag so that code runs only once every tick
 timeCounter[0] = timeInterval[0]; // setup the next tick
 red = false;
 green = false;
 blink = true;
 }
// -------------------------------------------------------------------
 if (mainTick) { // can have multiples of these
 mainTick = false; // clear the flag in the last one
 }
// -------------------------------------------------------------------
 digitalWrite(redLED , red ? HIGH:LOW); // C++ ternary operator
 digitalWrite(greenLED, green ? HIGH:LOW);
 digitalWrite(redLED , blink && subTick? HIGH:LOW); // subTick changes every 500 ms
}

• Russell McMahon: Your Wokwi link is broken.
• jsotola: @RussellMcMahon I tested the link on multiple devices, none of which were logged into Wokwi ... they all worked ... are you able to reach wokwi.com ?
• Russell McMahon: It works for me now. I was able to access Wokwi. I tried accessing it only a few minutes after you posted the link. Mayhaps there was some setup time. || They need an NRF24L01 peripheral, or better still, a mesh of them :-). (That would be useful to me at present).
• jsotola: @RussellMcMahon they have a "custom chip" available ... it can be programmed with C++, Rust and Verilog ... perhaps it could be made to emulate an NRF24L01