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Running Multiple Programs Simultaneously on Arduino

Running Multiple Programs Simultaneously on Arduino

January 12, 2025 Digital
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Running two programs simultaneously on Arduino can be a bit tricky because most Arduino boards are single-threaded, meaning they can only execute one instruction at a time. However, you can achieve concurrent behavior by using techniques such as non-blocking code, state machines, or interrupts. This article will guide you through these methods and provide practical examples to help you implement them.

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1. Non-Blocking Code

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This approach involves using the millis function to manage timing without blocking the program. You can periodically check conditions and execute tasks based on elapsed time.

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unsigned long previousMillis1  0;
"               "unsigned long previousMillis2  0;
"               "const long interval1  1000;  // Interval for Task 1: 1 second
"               "const long interval2  500;   // Interval for Task 2: 0.5 seconds
"               "
"               "void setup() {
"               "  (9600);
"               "}
"               "
"               "void loop() {
"               "  unsigned long currentMillis  millis();
"               "
"               "  // Task 1
"               "  if (currentMillis - previousMillis1  interval1) {
"               "    previousMillis1  currentMillis;
"               "    /* Perform task 1 */
"               "  }
"               "
"               "  // Task 2
"               "  if (currentMillis - previousMillis2  interval2) {
"               "    previousMillis2  currentMillis;
"               "    /* Perform task 2 */
"               "  }
"               "}
"               "
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2. State Machines

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Using a state machine allows you to manage different states of your program. Each loop iteration can check which state to execute.

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enum State { STATE1, STATE2 };
"               "State currentState  STATE1;
"               "
"               "void setup() {
"               "  (9600);
"               "}
"               "
"               "void loop() {
"               "  switch (currentState) {
"               "    case STATE1:
"               "      /* Perform task for STATE1 */
"               "      /* Switch to the next state based on some condition */
"               "      currentState  STATE2;
"               "      break;
"               "    case STATE2:
"               "      /* Perform task for STATE2 */
"               "      /* Switch back to the first state based on some condition */
"               "      currentState  STATE1;
"               "      break;
"               "  }
"               "}
"               "
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3. Using Interrupts

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If you have tasks that need to respond to external events, like button presses, you can use interrupts to handle these events without blocking the main loop.

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volatile bool taskFlag  false;
"               "
"               "void setup() {
"               "  (9600);
"               "  attachInterrupt(digitalPinToInterrupt(2), handleInterrupt, RISING); // Interrupt on pin 2
"               "}
"               "
"               "void loop() {
"               "  if (taskFlag) {
"               "    taskFlag  false;  // Reset the flag
"               "    /* Perform task when interrupt occurs */
"               "  }
"               "}
"               "
"               "void handleInterrupt() {
"               "  taskFlag  true;  // Set the flag when interrupt occurs
"               "}
"               "
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Conclusion

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By using non-blocking code, state machines, or interrupts, you can effectively run multiple tasks simultaneously on Arduino. Each of these methods has its own set of advantages and can be used depending on the specific requirements of your project.

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