[image] 6v6gt: The OP's example looks close enough to the one here for the ESP32 Arduino 3.x core. I am using ESP32 core 3.1.1 think the problem is timerbegin() initializes the timer and starts it the following timerstart() attempts to start the timer again and throws the exception E (20) … Answer from horace on forum.arduino.cc
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Espressif
docs.espressif.com › projects › arduino-esp32 › en › latest › api › timer.html
Timer - - — Arduino ESP32 latest documentation
#include <Arduino.h> #include "esp_system.h" #include "rom/ets_sys.h" const int button = 0; //gpio to use to trigger delay const int wdtTimeout = 3000; //time in ms to trigger the watchdog hw_timer_t *timer = NULL; void ARDUINO_ISR_ATTR resetModule() { ets_printf("reboot\n"); esp_restart(); } void setup() { Serial.begin(115200); Serial.println(); Serial.println("running setup"); pinMode(button, INPUT_PULLUP); //init control pin timer = timerBegin(1000000); //timer 1Mhz resolution timerAttachInterrupt(timer, &resetModule); //attach callback timerAlarm(timer, wdtTimeout * 1000, false, 0); //set
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Espressif Docs
espressif-docs.readthedocs-hosted.com › projects › arduino-esp32 › en › latest › api › timer.html
Timer — Arduino-ESP32 2.0.14 documentation
#include "esp_system.h" #include "rom/ets_sys.h" const int button = 0; //gpio to use to trigger delay const int wdtTimeout = 3000; //time in ms to trigger the watchdog hw_timer_t * timer = NULL; void ARDUINO_ISR_ATTR resetModule() { ets_printf("reboot\n"); esp_restart(); } void setup() { Serial.begin(115200); Serial.println(); Serial.println("running setup"); pinMode(button, INPUT_PULLUP); //init control pin timer = timerBegin(1000000); //timer 1Mhz resolution timerAttachInterrupt(timer, &resetModule); //attach callback timerAlarm(timer, wdtTimeout * 1000, false, 0); //set time in us } void lo
Discussions

Hardware Timer ESP32 Dev Module
Nano ESP32 category you chose is only used for discussions directly related to the Arduino Nano ESP32 board · In the future, please take the time to pick the forum category that best suits the subject of your question. There is an "About the _____ category" topic at the top of each category ... More on forum.arduino.cc
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July 19, 2024
Making a timer
Hello, I am making a Timer with my LCD Display. I do not have any input connected at this point in time. I am trying to make my timer display count down but I do not know how I can do this. I was hoping someone may assist me with the coding of this. I have not touched arduino in a while so ... More on forum.arduino.cc
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19
0
May 23, 2015
Creating and resetting timer
Hey, running into a problem which probably has a simple solution. I'm attempting to create a queue using switches which will then be displayed on a webpage for public perusal. IE switch #1 is on, a message will appear that states "switch 1 has been on and waiting for (blah blah hours:minut... More on forum.arduino.cc
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0
0
February 1, 2020
Timer functions?
Hello community 😁 I am a complete newbie at this. I am wondering about the timers on the Arduino uno. Can the timers interpret how long a button has been pressed or can the timer tell when a sensor was activated and then deactivated? I am trying to create a device that has two functions. More on forum.arduino.cc
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July 3, 2021
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Arduino Forum
forum.arduino.cc › projects › programming
Programming timer interruption - Programming - Arduino Forum
February 6, 2025 - I'm posting here a simple project to create an interrupt timer on an ESP32 board for version 3.1.1 by Esspressif Systems. I had difficulties to find updated information to make this code, I hope it can be useful to someone ! This code creates an interrupt every 100ms and counts the number of ...
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Mechatronics LAB
mechatronicslab.net › home › lessons › esp32 arduino programming handbook › chapter 12: timers, delays & interrupts › timers for esp32 arduino programming
Timers for ESP32 Arduino Programming - Mechatronics LAB
Syntax Explanation timerBegin(0, 80, true) creates timer 0. The 80 is a prescaler, setting how fast the timer counts. timerAttachInterrupt() links the timer to your function. timerAlarmWrite() sets the interval—in this case one million microseconds, or one second.
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DeepBlue
deepbluembedded.com › home › blog › arduino timers [ultimate guide]
Arduino Timers [Ultimate Guide]
August 17, 2023 - Arduino Timers [Ultimate Guide Tutorial]. Arduino Timers Explained (Timer0, Timer1, Timer2) With Example Code. Hardware Timers Library
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Arduino
docs.arduino.cc › libraries › arduino-timer
arduino-timer | Arduino Documentation
Home / Programming / Library / ...m/contrem/arduino-timer · Timer library for delaying function calls · Simple non-blocking timer library for calling functions in / at / every specified units of time....
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Upsy
upesy.com › tutorials › esp32 › esp32 programming › arduino code › basics › timers
Timer ESP32 with Arduino Code: Master the time - uPesy
February 2, 2023 - It allows you to trigger an interrupt ... threshold = 1000000; // 64 bits value (limited to int size of 32bits) timer = timerBegin(timer_id, prescaler, true); timerAttachInterrupt(timer, &timer_isr, true); timerAlarmWrite(timer, threshold, ...
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Arduino Forum
forum.arduino.cc › projects › programming
Hardware Timer ESP32 Dev Module - Programming - Arduino Forum
July 19, 2024 - #include #include hw_timer_t *timer ... { pinMode(ledPin, OUTPUT); // Initialize timer 0 with a frequency of 1 Hz timer = timerBegin(0, 1); // Attach an ISR function to the timer timerAttachInterrupt(timer, &onTimer, true); ...
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CircuitDigest
circuitdigest.com › microcontroller-projects › arduino-timer-tutorial
Arduino Timer Tutorial - Using Arduino Timers with Examples
July 29, 2025 - Whether this is your first Arduino UNO timer code or you are moving into complex timing applications, this tutorial will cover everything you need to know, from an overview of some very basic timer concepts to implementing the complete and working circuit with push button controls and an LCD. ... What You'll Learn: Program Timer1 interrupts and configure registers for precise timing.
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DeepBlue
deepbluembedded.com › home › blog › esp32 timers & timer interrupt tutorial (arduino ide)
ESP32 Timers & Timer Interrupt Tutorial (Arduino IDE) – DeepBlueMbedded
February 17, 2025 - This function is used to change the prescaler (clock divider) value of the specified timer module. The initial prescaler value is usually specified when you first initialize the timer with timerBegin() function.
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Arduino
playground.arduino.cc › Code › Timer
Arduino Playground - HomePage
January 26, 2019 - The Arduino IDE can be configured to program a variety of microcontrollers, not just the ones found on the standard Arduino boards.
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Steve Zafeiriou
stevezafeiriou.com › arduino-timer
Understanding Arduino Timer: Guide for 2025
December 31, 2025 - Use the Arduino timer library for simplified programming in complex projects.
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Arduino Forum
forum.arduino.cc › projects › programming
Making a timer - Programming - Arduino Forum
May 23, 2015 - Hello, I am making a Timer with my LCD Display. I do not have any input connected at this point in time. I am trying to make my timer display count down but I do not know how I can do this. I was hoping someone may assist me with the coding of this. I have not touched arduino in a while so ...
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PCBSync
pcbsync.com › home › arduino information › arduino timers: precise timing without delay
Arduino Timers: Precise Timing Without delay - PCBSync
March 4, 2026 - Q: Can I use Arduino timers in interrupt service routines? A: Yes, but with critical limitations. You can read millis() and micros() in ISRs, but the values only update while interrupts are enabled. Never call delay() in an ISR—it won’t work and will hang your program.
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Arduino Forum
forum.arduino.cc › projects › programming
Creating and resetting timer - Programming - Arduino Forum
February 1, 2020 - Hey, running into a problem which probably has a simple solution. I'm attempting to create a queue using switches which will then be displayed on a webpage for public perusal. IE switch #1 is on, a message will appear that states "switch 1 has been on and waiting for (blah blah hours:minut...
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Arduino Forum
forum.arduino.cc › projects › general guidance
Timer functions? - General Guidance - Arduino Forum
July 3, 2021 - Hello community :grin: I am a complete newbie at this. I am wondering about the timers on the Arduino uno. Can the timers interpret how long a button has been pressed or can the timer tell when a sensor was activated a…
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ElectronicWings
electronicwings.com › esp32 › esp32-timer-interrupts
ESP32 Timer Interrupts | ESP32
/* Timer Interrupt in ESP32, Alarm ...(&timerMux); } void setup() { Serial.begin(115200); pinMode (LED_PIN, OUTPUT); timer = timerBegin(0, 80, true); // timer 0, prescalar: 80, UP counting timerAttachInterrupt(timer, &onTimer, true); ...
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DeepBlue
deepbluembedded.com › home › blog › arduino-timer library & examples
Arduino-Timer Library & Examples
August 17, 2023 - Arduino-Timer Library & Examples. Arduino Timer Library Tutorial With Example Code Timer Applications, delay, Periodic Tasks, etc
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Arduino Forum
forum.arduino.cc › projects › programming
ESP32 Timer Interrupt - Programming - Arduino Forum
June 10, 2024 - Hi Folks, I am using Esp32 Dev Module to develop the timer interrupt code .but when I am using timerBegin() function I am getting errors like that: timerBegin() function can accept only one argument.Please help me out t…
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Free Hardware
en.hwlibre.com › free hardware › arduino › arduino timer: play with timing in your projects
Arduino Timer: play with timing in your projects - Hardware libre
April 1, 2022 - There are 3 timers on the plates Arduino UNO, although there may be more on other top plates: ... timer 0: 8-bit, can count from 0 to 255 (256 possible values). Used by functions like delay(), millis(), and micros(). Its modification is not recommended so as not to alter the programs.