![\"MicroPython](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP32-ESP8266-Timer-Interrupts-MicroPython.jpg?resize=1200%2C675&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nTable of Contents:<\/strong><\/p>\n\n\n\n In this tutorial, we’ll cover the following subjects:<\/p>\n\n\n\n Before proceeding with this tutorial, make sure you check the following prerequisites<\/p>\n\n\n\n To follow this tutorial you need MicroPython firmware installed in your ESP32 or ESP8266 boards. You also need an IDE to write and upload the code to your board. We suggest using Thonny IDE or uPyCraft IDE:<\/p>\n\n\n\n If you like to program using VS Code, there’s also an option: MicroPython: Program ESP32\/ESP8266 using VS Code and Pymakr<\/a><\/p>\n\n\n\n Learn more about MicroPython: MicroPython Programming with ESP32 and ESP8266<\/a><\/p>\n\n\n\n To complete the examples in this tutorial you need the following parts:<\/p>\n\n\n\n You can use the preceding links or go directly to MakerAdvisor.com\/tools<\/a> to find all the parts for your projects at the best price!<\/p> Interrupts are useful for making things happen automatically in microcontroller programs and can help solve timing problems. Interrupts and event handling provide mechanisms to respond to events, enabling the ESP32\/ESP8266 to react quickly to changes without continuous polling (continuously checking the current value of a pin or variable or continuously checking the time).<\/p>\n\n\n\n Using timer interrupts is especially useful to make something happen periodically or after a predefined period without constantly checking the elapsed time.<\/p>\n\n\n\n There are different types of interrupts: external interrupts and timed interrupts:<\/p>\n\n\n\n The MicroPython machine<\/span> module comes with a class called Timer<\/span> that provides methods to execute a callback function periodically within a given period or once after some predefined delay. This is useful for scheduling events or running periodic tasks without constantly checking the elapsed time.<\/p>\n\n\n\n Let\u2019s take a quick look at the Timer<\/span> constructors.<\/p>\n\n\n\n To create a timer, you simply need to call the Timer()<\/span> constructor and pass as argument the timer id, as follows:<\/p>\n\n\n\n Then, you initialize a timer using the init()<\/span> method on the Timer()<\/span> object and you pass as argument the timer mode, period, and the callback function. Here\u2019s an example:<\/p>\n\n\n\n This initializes a periodic timer that will run the timer_callback<\/span> function every 1000 milliseconds (1 second). You can change the period parameter to any desired period.<\/p>\n\n\n\n Instead of calling the callback function periodically, you may also want to run it once after a predefined time. For that, you can use the Timer.ONE_SHOT<\/span> mode as follows:<\/p>\n\n\n\n This line of code configures a timer (my_timer<\/span>) to run in a one-shot mode, triggering the specified callback function (timer_callback<\/span>) after 1000 milliseconds.<\/p>\n\n\n\n Learn more about the Timer class in the MicroPython documentation<\/a>.<\/p>\n\n\n\n We’ll now take a look at different application scenarios of timer interrupts with the ESP32\/ESP8266.<\/p>\n\n\n\n In this example, you\u2019ll learn how to blink an LED using a Timer. This will help you understand how periodic timers work.<\/p>\n\n\n\n We\u2019ll blink an LED connected to GPIO 13. So, wire an LED to the ESP32 or ESP8266 on that GPIO. You can use the following diagrams as a reference.<\/p>\n\n\n\n ESP32<\/strong><\/p>\n\n\n Recommended reading: ESP32 Pinout Reference: Which GPIO pins should you use?<\/a><\/p>\n\n\n\n ESP8266 NodeMCU<\/strong><\/p>\n\n\n Recommended reading: ESP8266 Pinout Reference: Which GPIO pins should you use?<\/a><\/p>\n\n\n\n The following example uses the Timer<\/span> class to blink an LED every half a second. This code is compatible with ESP32 and ESP8266 boards.<\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n In this code, we create a timer called blink_timer<\/span>:<\/p>\n\n\n\n Then, we initialize the timer with the following parameters:<\/p>\n\n\n\n This means this timer will call the toggle_led<\/span> function every 500, forever (or until you stop the program).<\/p>\n\n\n\n The toggle_led<\/span> function, as the name suggests, will toggle the LED state:<\/p>\n\n\n\n The timer callback functions must have one argument that is passed automatically by the Timer<\/span> object when the event is triggered.<\/p>\n\n\n\n With timers, you can also have other tasks running on the main loop without interfering with each other. For example, in our case, in the main loop, we\u2019ll print a message every two seconds.<\/p>\n\n\n\n When the user stops the program (KeyboardInterrupt<\/span>), we deinitialize the timer using the deinit()<\/span> method and turn off the LED.<\/p>\n\n\n\n With an LED connected to GPIO 13, run the previous code on your board.<\/p>\n\n\n\n You\u2019ll get the message \u201cMain Loop is running\u201d every two seconds on the Shell, while the LED is blinking every half a second at the same time.<\/p>\n\n\n After testing the previous example, it\u2019s easy to understand that if you create multiple timers, you can run multiple tasks at different frequencies. In this example, we\u2019ll blink two different LEDs. One will blink every half a second, and the other one every two seconds.<\/p>\n\n\n\n Wire two LEDs to the ESP32\/ESP8266 (to distinguish between the different LEDs, we\u2019ll use different colors):<\/p>\n\n\n\n You can use the following diagrams as a reference to wire the circuit.<\/p>\n\n\n\n ESP32<\/strong><\/p>\n\n\n ESP8266 NodeMCU<\/strong><\/p>\n\n\n The following code uses Timers to blink two different LEDs at different frequencies. The code is compatible with ESP32 and ESP8266 boards.<\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n In this code, we create two different timers, one for each LED:<\/p>\n\n\n\n Then, we call the corresponding callback functions at different intervals:<\/p>\n\n\n\n The callback functions simply toggle the current LED value:<\/p>\n\n\n\n Run the previous code on the ESP32 or ESP8266. You\u2019ll notice that the two LEDs will blink at different frequencies.<\/p>\n\n\n\n At the same time, you\u2019ll get a message from the while loop every two seconds. This shows that the other tasks don\u2019t interfere with our loop.<\/p>\n\n\n Button bouncing is when the pushbutton will count more than one press when in fact, you just pressed one time. This is very common in mechanical buttons like pushbuttons.<\/p>\n\n\n This happens because the electrical contacts inside the button connect and disconnect very quickly before reaching a steady state, which will cause the system to register multiple press events, causing an inaccurate count. To prevent this issue, we can add some debouncing techniques using delays or timers.<\/p>\n\n\n\n In this example, we’ll take a look at how you can use timers and events to debounce a pushbutton.<\/p>\n\n\n\n For this example, wire an LED (GPIO 13) and a pushbutton (GPIO12) to the ESP32 and ESP8266.<\/p>\n\n\n\n You can use the following schematic diagrams as a reference.<\/p>\n\n\n\n ESP32<\/strong><\/p>\n\n\n ESP8266 NodeMCU<\/strong><\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n Let’s take a quick look at how we use timers to debounce a pushbutton.<\/p>\n\n\n\n\n
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Prerequisites<\/h2>\n\n\n\n
MicroPython Firmware<\/h3>\n\n\n
![\"micorpython](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/02\/micropython-logo.png?resize=150%2C150&quality=100&strip=all&ssl=1\"){kind=logo}
<\/figure><\/div>\n\n\n\n
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Parts Required<\/h3>\n\n\n\n
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![](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/10\/header-200.png?w=1200&quality=100&strip=all&ssl=1\")
<\/a><\/p>\n\n\n\nIntroducing Interrupts<\/h2>\n\n\n\n
Types of Interrupts<\/h3>\n\n\n\n
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The MicroPython class Timer<\/em><\/h2>\n\n\n\n
Creating a Timer<\/h3>\n\n\n\n
my_timer = Timer(id)<\/code><\/pre>\n\n\n\nmy_timer.init(mode=Timer.PERIODIC, period=1000, callback=timer_callback)<\/code><\/pre>\n\n\n\nmy_timer.init(mode=Timer.ONE_SHOT, period=1000, callback=timer_callback)<\/code><\/pre>\n\n\n\nTimer Interrupts with the ESP32\/ESP8266<\/h2>\n\n\n\n
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1. Blinking an LED with a Timer – MicroPython<\/h3>\n\n\n\n
Circuit Diagram<\/h4>\n\n\n\n
![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP32-with-LED-circuit.png?resize=788%2C774&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"ESP8266](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP8266-LED_circuit.png?resize=575%2C875&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nCode<\/h4>\n\n\n\n
# Rui Santos & Sara Santos - Random Nerd Tutorials\r\n# Complete project details at https:\/\/RandomNerdTutorials.com\/micropython-timer-interrupts-ep32-esp8266\/\r\n\r\nfrom machine import Pin, Timer\r\nfrom time import sleep\r\n\r\n# LED pin\r\nled_pin = 13\r\nled = Pin(led_pin, Pin.OUT)\r\n\r\n# Callback function for the timer\r\ndef toggle_led(timer):\r\n led.value(not led.value()) # Toggle the LED state (ON\/OFF)\r\n\r\n# Create a periodic timer\r\nblink_timer = Timer(1)\r\nblink_timer.init(mode=Timer.PERIODIC, period=500, callback=toggle_led) # Timer repeats every half second\r\n\r\ntry:\r\n # Main loop (optional)\r\n while True:\r\n print('Main Loop is running')\r\n sleep(2)\r\nexcept KeyboardInterrupt:\r\n # Keyboard interrupt occurred, deinitialize the timer\r\n blink_timer.deinit()\r\n print('Timer deinitialized')\r\n # Turn off the LED\r\n led.value(0)\r\n<\/code><\/pre>\n\tblink_timer = Timer(1)<\/code><\/pre>\n\n\n\nblink_timer.init(mode=Timer.PERIODIC, period=500, callback=toggle_led)<\/code><\/pre>\n\n\n\n# Callback function for the timer\ndef toggle_led(timer):\n led.value(not led.value()) # Toggle the LED state (ON\/OFF)<\/code><\/pre>\n\n\n\nwhile True:\n print('Main Loop is running')\n sleep(2)<\/code><\/pre>\n\n\n\nexcept KeyboardInterrupt:\n # Keyboard interrupt occurred, deinitialize the timer\n blink_timer.deinit()\n print('Timer deinitialized')\n # Turn off the LED\n led_pin.value(0)<\/code><\/pre>\n\n\n\nTesting the Code<\/h4>\n\n\n\n
![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/blinking-led-timer-esp32-esp8266.png?resize=729%2C302&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP32-blinking-led-1.jpg?ssl=1\")
<\/figure><\/div>![\"\"](\"https:\/\/i1.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP32-blinking-led-2.jpg?ssl=1\")
<\/figure><\/div><\/div><\/div><\/div><\/div>\n\n\n\n
\n\n\n\n2. Blinking Multiple LEDs at Different Frequencies<\/h3>\n\n\n\n
Circuit Diagram<\/h4>\n\n\n\n
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![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP32-with-two-LEDs-circuit.png?resize=670%2C823&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"ESP8266](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP8266-2-LEDs_bb_circuit.png?resize=647%2C857&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nCode<\/h4>\n\n\n\n
# Rui Santos & Sara Santos - Random Nerd Tutorials\r\n# Complete project details at https:\/\/RandomNerdTutorials.com\/micropython-timer-interrupts-ep32-esp8266\/\r\n \r\nfrom machine import Pin, Timer\r\nfrom time import sleep\r\n\r\n# LEDs\r\nred_led_pin = 12\r\nred_led = Pin(red_led_pin, Pin.OUT)\r\nyellow_led_pin = 13\r\nyellow_led = Pin(yellow_led_pin, Pin.OUT)\r\n\r\n# Callback function for the red timer\r\ndef toggle_red_led(timer):\r\n red_led.value(not red_led.value()) # Toggle the LED state (ON\/OFF)\r\n print('red LED is: ', red_led.value())\r\n\r\n# Callback function for the yellow timer\r\ndef toggle_yellow_led(timer):\r\n yellow_led.value(not yellow_led.value()) # Toggle the LED state (ON\/OFF)\r\n print('yellow LED is: ', yellow_led.value())\r\n\r\n# Create periodic timers\r\nred_timer = Timer(1)\r\nyellow_timer = Timer(2)\r\n\r\n# Init the timers\r\nred_timer.init(mode=Timer.PERIODIC, period=500, callback=toggle_red_led) # Timer repeats every 0.5 second\r\nyellow_timer.init(mode=Timer.PERIODIC, period=2000, callback=toggle_yellow_led) # Timer repeats every 2 seconds\r\n\r\ntry:\r\n # Main loop (optional)\r\n while True:\r\n print('Main Loop is running')\r\n sleep(2)\r\n \r\nexcept KeyboardInterrupt:\r\n # Keyboard interrupt occurred, deinitialize the timers\r\n red_timer.deinit()\r\n yellow_timer.deinit()\r\n print('Timers deinitialized')\r\n # Turn off the LEDs\r\n yellow_led.value(0)\r\n red_led.value(0)\r\n\r\n<\/code><\/pre>\n\t# Create periodic timers\nred_timer = Timer(1)\nyellow_timer = Timer(2)<\/code><\/pre>\n\n\n\n# Init the timers\nred_timer.init(mode=Timer.PERIODIC, period=500, callback=toggle_red_led) # Timer repeats every 0.5 second\nyellow_timer.init(mode=Timer.PERIODIC, period=2000, callback=toggle_yellow_led) # Timer repeats every 2 seconds<\/code><\/pre>\n\n\n\n# Callback function for the red timer\ndef toggle_red_led(timer):\n red_led.value(not red_led.value()) # Toggle the LED state (ON\/OFF)\n print('red LED is: ', red_led.value())\n\n# Callback function for the yellow timer\ndef toggle_yellow_led(timer):\n yellow_led.value(not yellow_led.value()) # Toggle the LED state (ON\/OFF)\n print('yellow LED is: ', yellow_led.value())<\/code><\/pre>\n\n\n\nTesting the Code<\/h4>\n\n\n\n
![\"ESP32](\"https:\/\/i2.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/1-ESP32-ESP8266-blinking-leds-with-timers.JPG.jpg?ssl=1\")
<\/figure><\/div>![\"ESP32](\"https:\/\/i1.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/2-ESP32-ESP8266-blinking-leds-with-timers.JPG.jpg?ssl=1\")
<\/figure><\/div><\/div>![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/3-ESP32-ESP8266-blinking-leds-with-timers.JPG.jpg?ssl=1\")
<\/figure><\/div>![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/4-ESP32-ESP8266-blinking-leds-with-timers.JPG.jpg?ssl=1\")
<\/figure><\/div><\/div><\/div><\/div><\/div>\n\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP32-ESP8266-Blinking-LEDs-timers-micropython.png?resize=672%2C375&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n
\n\n\n\n3. Debouncing a Pushbutton with a Timer<\/h3>\n\n\n\n
![\"Debouncing](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/debouncing-pushbutton.jpg?resize=860%2C529&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nCircuit Diagram<\/h4>\n\n\n\n
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![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP32-LED-pushbutton_bb-1.png?resize=692%2C855&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/ESP8266-LED-pushbutton_bb.png?resize=625%2C854&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nCode<\/h4>\n\n\n
# Rui Santos & Sara Santos - Random Nerd Tutorials\r\n# Complete project details at https:\/\/RandomNerdTutorials.com\/micropython-timer-interrupts-ep32-esp8266\/\r\n \r\nfrom machine import Pin, Timer\r\nimport time\r\n\r\nled = Pin(13, Pin.OUT)\r\nbutton = Pin(12, Pin.IN, Pin.PULL_UP)\r\ncounter = 0 # Initialize the button press count\r\ndebounce_timer = None\r\n\r\ndef button_pressed(pin):\r\n global counter, debounce_timer # Declare variables as global\r\n\r\n if debounce_timer is None:\r\n counter += 1\r\n print("Button Pressed! Count: ", counter)\r\n \r\n # Toggle the LED on each button press\r\n led.value(not led.value())\r\n\r\n # Start a timer for debounce period (e.g., 200 milliseconds)\r\n debounce_timer = Timer(1)\r\n debounce_timer.init(mode=Timer.ONE_SHOT, period=200, callback=debounce_callback)\r\n\r\ndef debounce_callback(timer):\r\n global debounce_timer\r\n debounce_timer = None\r\n\r\n# Attach the interrupt to the button's rising edge\r\nbutton.irq(trigger=Pin.IRQ_RISING, handler=button_pressed)\r\n\r\ntry:\r\n # Main loop (optional)\r\n while True:\r\n print("Loop is running")\r\n time.sleep(5)\r\nexcept KeyboardInterrupt:\r\n # Keyboard interrupt occurred, deinitialize the timer\r\n debounce_timer.deinit()\r\n # Turn off the LED\r\n led.value(0)<\/code><\/pre>\n\tHow the Code Works<\/h4>\n\n\n\n