Reading this forum has been game changing for a new arduino user like myself. By using a delay (0) the author thinks they are saying "I don't want to delay here, but if anything is using the yield () function it can run now. millis () is one of the fastest function of the Arduino core. Button logic gets quite involved when using millis() to do things like debouncing , double click, press and hold and such. Arduino Timer Interrupts. When a Pin has been configured for INPUT with pinMode (), simply use digitalWrite () to write a HIGH to that pin. I tried adding an if statement like the one below but it seems like the delay line is preventing it from happening since it goes directly to case 3. – harun caliskanoglu. The millis feature of the Arduino Code allows the Arduino to display the functions up to the value in milliseconds to 100% accuracy. Don't use 'int. Returns the number of milliseconds since the Arduino board began running the current program. A timer is more about how much time has passed since it was arbitrarily started/reset, the actual time it was started and stopped is irrelevant. While studying how millis () and micros () in the millis () function which causes the returned millisecond value to incrementally drift 296us / ~71 minutes (2^32 us) of operation. like every 59 days or whatever. And since the maximum value millis() can 'hold' is 4,294,967,295 that still gives room for. system January 25, 2012, 3:47pm #2. Zero = Uptime 0 days 00:00:00. If my counter goes to 16 and then I press reset through pin 7, I will get 0 6. Improve this answer. How to reset a millis () variable back to zero. After the set commands are executed, the program resumes again from the same position. Only 1000 milliseconds (approximately) has elapsed, so the motor stays running. The same you started the process. It starts at 0 each time the board is reset and is incremented each millisecond by a CPU hardware counter. It executes very quickly and has a good resolution (milliseconds). This function is used to configure the timer. And you could reset the millis counter by making an extern variable declaration for it in your sketch and setting it to zero, but you might expect "bad things" to happen in any other bit of code that was using millis() for timing. My millis() code is attached,. After approximately 50 days (or a bit more than 49. millis () is a built-in method that returns the number of milliseconds since the board was powered up. You may find the time library Arduino Playground - Time will do what you want. g. The Arduino programming language Reference, organized into Functions, Variable and Constant,. jremington July 25, 2016, 4:13pm 2. If you instead set previousMillis to: previousMillis = 0 - (interval - 5); Then you will get the behavior you expect I think. millis () uses timer0 (linked to CPU clock) to count time, but ADC_sleep mode stops the CPU clock, therefore millis () will drift (lag behind) after each ADC conversion performed in ADC_sleep mode. I guess that is a approach to reset the timer used by the millis () function. Just like your clock does. 7 days for millis(), 71+ hours for micros(). The reset to zero is not a problem if you use millis() properly by which I mean you use subtraction of period start time from current time to determine whether the required period has elapsed mllis() returns an unsigned long, but the reason why the reset to zero does not matter is easier to understand using smaller numbers such as 0 to 255. If you look at the code that gets slowly typed over the first four minutes of the video you referenced you will see that he sets 'cur_time' to millis () - pre_time and sets pre_time to millis () when he wants to re-start the timer. Is there an example of this? I've been looking at a lot of. If the sketch is intended to run for longer than that, It needs to make sure the rollover does not make the sketch fail. Yield processing to other threads through the yield () weak symbol. However, you must save the start time when the start conditions become true rather than when they are true. Then if it sees that the button is not pressed, within your set time, it sets the case back to zero. Because you set it to 0 on line 137 I guess: loopCounter = 0; //resets loop counter to 0. When that occurs take the required action (s) and save the value millis () again as the start of the. Hi @say2k. 7 day window) could be very hazardous, depending on how the time frames line up. const byte interrupt_Pin = 2; //Sets the pin used for the. c=500ms after b. That is not needed. print (" "); } The board wasn't exiting the while loop, so I included serial. "Reset the whole arduino!!" I figure this might work just because if the timer is not on I really don't care if it is resting itself or messing with millis(). Its maximum value is directly related with the used variable, unsigned long. This is why, it is very important to not use any. 192 KHz. millis () push button LED timer demo example coding. The simplest way is to detect a change of date. 4,294,967,295 / 1000 = 4,294,967 seconds. From here, I have attempted to add millis() coding to get a timer working between the two inputs however the serial monitor is coming up entirely empty. If it has a second microcontroller that it always on (like the Uno), you should find a way to disable it. Hello, I have a switch which uses a, ESP8266 and relay module connected to it. 71 days. If you find this number at startup, it is extremely likely that the program is starting from a warm reset. int MotorControl6 = 6; int MotorControl7 = 7; int MotorControl4 = 4; // the setup routine runs once when you press. BLOG# 4- BPM Uno – System Implementation and Testing. what I want to add A2 as A reset button. The millis function is meant to get the elapsed milliseconds since the program started. static unsigned long previousMicros = 0; There is no need to reset micros (). The best part is; if you can set the pin to OUTPUT, you can use this technique. What I want to do is to constantly poll the digitalRead of GPIO_0 and GPIO_2 for a period of one hour. While the interrupts are off, check pulsecount. Hi there, kinda random question. But by itself, the above will never allow m to go down again, even if the peaks are lower. UKHeliBob November 13, 2022, 3:37pm 2. sprintf(tweet,"%d Sensor Reading S1=%e S2=%e", millis, (float)temp_f, (float)real_humidity); //Your tweet message But millis of course is just the ms it's been running in raw form which quickly becomes a huge string. if at anytime during the timer weight >125 then stop the timer. 25) Adafruit_BME280 bme; int t_interval = 5000;. millis () is the same. @runciblefish. const byte interrupt_Pin = 2; //Sets the pin used for the. Example 3: Measuring Button Press Duration. cc millis() - Arduino Reference. Because, if millis is reset in loop,endtimex will be 0,1000,2000. The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3. Just keep track, subtract and compare whatever time values you’re using. I'd like if we press the first the millis () counter starts. I somehow want to generate a "running average" over a minute so I can produce a "strikes per minute" value. 000 End of first day = Uptime 0 days 23:59:59. 32 KHz. Once setup () is finished, Arduino calls the loop () method over and over again. 0 License. The accumulated time of the Millis-Counter could be read at any time using the following command: unsigned long presentMillis = millis (); 3. indeed you should confirm or correct what @johnwasser was asking. So we can count up to 49. Never reset millis(); simply record its value when an action occurs and use a comparison between the later value and the earlier value to determine the amount of time that has passed. When you have finished, subtract the recorded time from the current time, to find the elapsed time. 1 Answer. The reference guide tells me that millis () provides a value of data type unsigned long. I have a program which measures temperatures every 30 minutes and sends them to a database. Now, you can design your program as follows: (1) Keep your lamp at OFF position. More about millis () later. If it has a second microcontroller that it always on (like the Uno), you should find a way to disable it. print (millis ()) inside the loop to check the value of millis (), and realized that my millis () function was only returning zero. At the start of each timing period print the value of the counter. I have been searching all day long for there seem a problem in my coding. Controlling Millis () Using Arduino Programming Questions. Hello, I have a library that I got off the internet. You can reset millis by restarting the arduino. I thank you all. Blinking one LED with millis () and another with Timer/Counter1. davisdesigns October 9, 2015, 4:05am 1. . the DHT temperature sensor may be read once per 2 seconds, if a DHT library remembers the last read in millis it can guard the sensor. jammcooter May 2, 2021, 11:21pm 1. ino to run 400 millis-timer on a Arduino Uno. millis () is likely to always be greater than zero. The type of Arduino I am using is: "Arduino Uno", and Arduino IDE Version is 1. Bacause depending on what you are doing with millis(), and what board you have, you can make your arduino do weird things after it fills up the memory with millis(). uint32_t lastResetWas; void setup () { lastResetWas = millis ();. I think there is no need of disabling it. By my calculation this should roll-over after 1193 hours (~50 days), assuming the full 32 bits are used. Just like your clock does. system March 28, 2012, 9:04pm 4. From then on the code works fine. [arduino firstline=”7″] unsigned long turnOnDelay = 2500; // wait to turn on LED unsigned long turnOffDelay = 5000; // turn off LED after this timeInterrupts allow certain important tasks to happen in the background and are enabled by default. Returns. And since the maximum value millis() can 'hold' is 4,294,967,295 that still gives room for almost 50 rollovers before the original value rolls over Using millis() to decide when to make the only call to this code in a single "wrap" of millis (a specific 49. I somewhere heard that it could work even in power-save mode but thats not important for now. The count is working well. 999 Second day 86400000 = Uptime 1 days 00:00:00. e. Sorted by: 10. you don't get every millisecond in the draw cycle, because each program cycle needs more than a millisecond. println(time); //prints time since program started delay(1000); // wait a second so as. The timer does not stop. If the sketch is intended to run for longer than that, It needs to make sure the rollover does not make the sketch fail. I have searched this forum and Google high and low, but have yet to find a straightforward answer to this: Can millis be used after a button? I have reviewed the newbie posts here and tried as many examples as I could find that are relevant but I just can't seem to figure this one out. I'm making an RPM counter that reads a square wave from 0-5v. Using board reset button that resets program & all values to it's start wont help. For safety, if using millis() to determine when to make the only calls to millis64(), there should be at least two calls in every 49. Correct. Project Overview. This is my first experience with Arduino and millis () is too involved for me. On each call you get the actual time and the difference to starttime is the time, where the program. Even signed long may encounter errors as its maximum value is half that of its unsigned counterpart. Internally, Time depends upon Arduino's millis() function to keep track to elasped time. println (millis () / 1000. You can store the current time in a timeval struct variable with gettimeofday function on startup. If you want to turn it of, regardless of the button state, you can add a boolean flag to your if-statement, to set the timestamp only, when the button was pressed first: In this case you have to reset the button_pressed variable to false, when you are. While it is not a good idea to reset millis, it can be done easily:The demo Several Things at a Time illustrates the use of millis() to manage timing without blocking. So you could regularly reset m to be equal to the latest reading, even if that reading is lower than m. The library makes use of the timer 1 to send data. I used the 16-bit unsigned int in my millis_overdone. Hello, I have a library that I got off the internet. This potential issue can very easily be avoided with a small alteration to the code from last time. A software reset resets millis(). More about millis () later. update function. At first, you might be thinking, well that’s not every useful! But consider how you tell time during the day. Those can be affected. 295 If millis() > 4294967295 then Arduino reset millis(). When you perform arithmetic between with char or unsigned char (int8_t and uint8_t are typedefs for these two data types), the result is promoted to a signed int type. The Arduino MKR Zero is a development board for music makers! With an SD card holder and dedicated SPI interfaces (SPI1), you are able to play music files without extra hardware. You will probably want to do something to stop the counter when it hits zero. it'd be 1 for odd and 0 for even numbers. Reset to default 0 first of all unsigned long nowTime; should be at the top. Delay wont work, it will ruin my Pulse In reading. Milis count the time since the program starts. So you can count on the time and perform certain tasks after a certain time. I'm now tidying up some bits and pieces, and so here is my question: When I select a value to vary (via one of six push buttons and a single rotary encoder) I need to 'hold' the relevant button state. Using Arduino. Port". answered Jan 6, 2020 at 11:00. millis () will wrap around to 0 after about 49 days (micros. I read somewhere that millis resets to zero and starts again which functionally does not affect the running of the program. I'm making an Arduino reverse stopwatch. Code samples in the. i. 5 minutes so just more than one hour. You can modify the stock Arduino Timer0 OVF to insert your own ISR. The first thing you need to do is debounce your buttons. Reset millis (); Using Arduino. Hi I'm having trouble turning on an LED for 3 seconds using a push button and the millis function. Reconfiguration of the microcontroller’s timers. These last four options are achieved by various combinations of the RS1 and RS2 control bits. and then recovers immediately because of the previousMillis=millis() reset,. If you start something, record the time. This happened after I added basetime=millis (); and currtime = millis ()-basetime;. Is it bad your clock overflows (goes back to zero) at midnight? No it isn't. Schematic diagram – Heartbeat sensor Arduino. Hello, i have a strange problem with USB. I've a sensible routine that checks for how long a button is pressed, I would use the variable millis() to calculate the difference and act according to it, in particular there may be 2 cases: the button is released before X millis or it keeps pressed (there may be some seconds). EllapsedMilliseconds (); Returns the. Option #2 is not really welcomed by a lot of people here. Use case statements for your LEDs. After successful setup the timer will automatically start. debouncing an interrupt trigger. But in the code, Timer 0 is disabled and so delay(), millis() etc won't work. When you stop resetting the timer the value of millis () - yourTimer begins to increase. Supports millis, micros, time rollover, and compile time configurable number of tasks. ". CenkayB July 26, 2021, 10:06am 1. As the returned variable is of type unsigned long, the number will overflow after 49 days and reset to zero. Global variables are initialized to zero and millis() starts at 0 so that is usually close enough. Well Perry, since you want to learn ways to reset 'millis()', as I recall, there is a little button on most of the Arduino boards called 'Reset'. Because you set it to 0 on line 137 I guess: loopCounter = 0; //resets loop counter to 0. 6. So, long answer short (no pun intended), you reset millis () by directly setting the variable that millis () uses to keep track of clock cycles to zero. After more than a month arduino won't detect water even if sensor is in water all time. Start a timer when button is pressed. There are libraries that use millis or micros timing to read sensors. Electrically noisy environment triggering a reset via the RESET pin. mondoha May 29, 2020, 1:12am 3. Except that, unlike a simple counter, it may miss certain values. For accurate timing over short intervals, consider using micros (). (It works when I remove those two but I added because I want the millis () to be reset to zero. 000 Last millis() complete day = Uptime 48 days 23:59:59. Returns the number of milliseconds since the Arduino board began running the current program. The maximum value of an unsigned long variable can be 2 32 – 1 or 4,294,967,295. 16 bit values process twice as fast as 32-bit values. I've looked on lots of forums and have tried a few. 024 milliseconds, then. A boolean is handy for doing this. It allows me to control RGB LED modules. Click on System, and open the Device Manager. Always prints the time since the Arduino reset. Please note that the return value for millis(). b707 November 22, 2023, 10:37pm 6. 0 software - I guess this was fixed and millis() now do really rollover only in 50 days, like it is said in documentation. Arduinoで、millis()をdelay()の代わりに待ち時間を経過したかを確認するために利用する際、millis()がオーバーフローしたときの挙動に関する実験です。 Arduino UnoとESP-WROOM-32について試してみました。 Arduinoのmillis()は、プログラムを起動してから経過した時間をミリ秒単位で返す関数です。in your code is it somehow possible to reset your Counter after it is finished ? At any time you can set 'countDown' to a new value and set 'lastTick' to millis() to start a new countdown. I need it to turn on for 3 second when the button is pushed briefly. I need the output to stay low for a interval after the sensor goes back to high. I am working on a timing function for a light switch and am testing some code to make sure I know how it works. the first lap begins counting when the arduino fires up. Because the only millis functions I have seen are for blinking leds but I don’t know how to apply it to my problem. On IOT2000 runs linux and has a internal clock. For accurate timing over short intervals, consider using micros (). StefanL38 April 23, 2023, 7:09am 6. println (println = print line) function to print the value of millis. Example,starttimex=4294947296. Using an LDR sensor, the Arduino will know when you are holding your bottle and should stop counting up to activate the lights and buzzer and reset once you let go of your bottle again. I've not been programming for long and I just want to expand from electronic engineering with an Arduino UNO board. The arduino millis () function is not a function that starts a timer. print (millis ()); Serial. . StefanL38 May 8, 2021,. int MotorControl5 = 5; // Arduino Pin to control the motor. Arduino millis () Function. This code manages to count up the amount of rising edges using an interrupt to increment whenever the input goes up to 5v, however I'm not sure how to reset the count back to zero without causing the output to just be zero. Hello all, So currently im creating a code where if no buttons are pressed on a series of buttons, a few neopixel Leds will begin to cycle through RGB. For safety, if using millis() to determine when to make the only calls to millis64(), there should be at least two calls in every 49. If you instead set previousMillis to: previousMillis = 0 - (interval - 5); Then you will get the behavior you expect I think. println (time); //prints time since program started delay (1000); // wait a second so. Millis () does not back to zero after woke up from deep sleep mode. timer0_millis = 0; // reset millis, will eliminate this in future startTime = millis. While input pin gets high for more than 10000 milli seconds output pin gets high. Nothing "bad" happens. When the maximum number is reached ( 0xFFFFFFFF) and more time passes, it will roll-over back to 0 ( 0x00000000) and start again. Run loop for a period of time then stop loop. d=2000ms. This code activates a relay (pin 5) if the flow count reaches 400 milliliters. Arduino Timer count resets at 65 but it should reset at 70. Arduino millis() Reset. Try to print this value: runciblefish:. So, using these timers is not a good suggestion if you plan to use above options. How would one internally to the arduino, reset the millis command. Using Arduino Microcontrollers. Do i need to reset CurrTime and StrobeTime to zero at the begining of the loop? Koepel December 14, 2022, 3:36pm 14. We mentioned one caveat with these functions, and that is that millis() and micros() overflow after around 50 days and 70 minutes, respectively. This drift is cumlative, i. That *difference *is what is compared to decide if time has. uint32_t resetAfterMillis = 30000; // Reset after 30 seconds. The code needs to run pretty fast, as it handles two inputs of a camshaft sensor, one is 1 cycle/rotation, the other is 6 cycle/rotation. ``` void (resetFunc) (void) = 0; // program reset function (set before main loop) // Hold both buttons down to reset program. millis () is a built-in method of the Arduino library, and it returns the number of milliseconds that the sketch has been running, or since the board has been powered up. Here’s the code. case 1:. ( millis () - timeValue ) equals elapsed time from setting timeValue = millis (). Continue begging for help. Nothing else in my code is timer sensitive, so I'd just as soon reset millis() to zero just prior to my need of adding 1000 to it, ever time. Using elapsedMillis makes this easy. ) When the result is 60,000 or bigger, there's yer minute. Use it as you would use the clock on the wall. Improve this answer. This number will overflow (go back to zero), after approximately 49 days. Project Overview. I found a very simple but working code for this project. jremington July 25, 2016, 4:13pm 2. Needed for Leonardo only } //link your buttos here button_blink_the_fog_lights. If output pin 13 high, then capture how millisecond until the pin 13 goto low. Hi there, kinda random question. Save the value of millis () when you want to start the timing period then each time through loop () test whether the required period has elapsed. case1: reset timeValue - done by timeValue = millis () set case = case1a. Then, remove the time = millis () statement from motorStop. Try the sketch in Wokwi here: millis_overdone. The return value of millis () function rolls over back to zero after roughly 50 days. . Arduino Forum HELP. what you wanna do is more like this: Copy code. I verified this behavior with my desktop C++ compiler using the std::is_same struct from. I've started a new project based on the Secret Knock Detecting Door Lock by Steve. Code for resetting millis (): Write before void setup: extern volatile unsigned long timer0_millis; Write this to reset where you want the millis () to reset: noInterrupts ();. h". All that happens, on a timer overflow, is that it goes back to zero and starts counting up again. If analogread bigger than 600, then digitalwrite 13, high. Est. Hi! Beginner here so pls bear with me. I have code that runs a stepper motor using the A4988 chip and I would like to use millis () instead of delay () as it interferes with the usb read. If you start something, record the time. When it rolls over to zero, my loop would fail. initialize the OLED Display and start displaying the measurement as zero. // fall through to. I'm not super critical about this being non-deterministic. At any given moment, exactly one LED (of four) is turned on (we are. Learning the software reset is a good thing if you are doing what I am doing. How can I format millis into a 24 hour display, [HH:MM:SS] that resets every 24 hours, or better yet, insert an authentic. odometer March 6, 2022, 7:35pm 30. case1a: count three instances of something. All without using the delay() function. Do you have any solutions? Or another RTC module which provides ms resolution instead. If it's non zero, store millis in an unsigned long. change to arduino IDE and press Ctrl-V to insert the complete code directly into the arduino-IDE. The library makes use of the timer 1 to send data. This number will overflow (go back to zero), after approximately 70 minutes. When the counter reaches 3 set it back to zero. Instead of trying to reset millis(), we will compare against itself later on. detach() to disconnect Ardunino Zero from PC and subsequentely the function USBDevice. h> int sec = 0; int mts = 0; int hrs = 0; LiquidCrystal lcd (4, 6, 10, 11, 12, 13); void setup () {. To prevent it from reaching zero, we continuously call it from the loop (), using the ArduinoCloud. . 024 milliseconds, then incrementing by 2 (rather than 1) every 41 or 42 ticks, to pull it back into synch; thus some millis () values are skipped. Here is how I measure the rotational speed of a pulse type anemometer (1 pulse per revolution), using simple input polling: unsigned long start, revtime; while (digitalRead(anem_input) == LOW); //wait for input to go high start=millis(); //reset timer while (digitalRead(anem_input) == HIGH); //wait for it to go low again while. Using Arduino. Number of milliseconds since the program started (unsigned long). The delay code is this: int flowPin = 2; //This is the input pin on the Arduino double flowRate; //This is the value we intend to. If the state is LOW and has not changed, I want it to automatically switch to high (ie: shut off the lights). Each time we press the first button one minute is added to that time. This potential issue can very easily be avoided with a small alteration to the code from last time. To answer the rest of your message, playMetronome() gets called from loop() so as to get the regular ticks I need. However, the current problem is that the start time is being determined on upload/reset to the board and not being. h> int sec = 0; int mts = 0; int hrs = 0; LiquidCrystal lcd (4, 6, 10, 11, 12, 13); void setup () { lcd. Put the intervals in an array and work your way through them as you change the state of the LED. Generally the reason people want to reset it, is that they are. On IOT2000 runs linux and has a internal clock. This code manages to count up the amount of rising edges using an interrupt to increment whenever the input goes up to 5v, however I'm not sure how to reset the count back to zero without causing the output to just be zero. Set the global variable that holds the saved-at-the-start milliseconds to the current value of. arduino programs are standalone programs without os. Once a button is pressed (may need to include debounce code), it will switch the case and start the timer (RCT, dont use delays). When you call the millis () function, it returns the current value of the timer/counter in milliseconds (hence the millis () function name). unsigned long time; void setup () { Serial. ) When the result is 60,000 or bigger, there's yer minute. Thats fine, i have done all of the above, but i think rollover problem will be still there as in currentTime if the maximum value of millis() arrives and after that instant millis() get reset and starts from zero so in currentTime there will be maximum value of millis() and from subtraction we will get negative number. The counter resets when the Arduino is reset, it reaches the maximum value or a new sketch is uploaded. Instead you just remember what millis () was when you pressed your start button, then subtract that from whatever millis () is showing at any other point in the future. Returns the number of milliseconds passed since the Arduino board began running the current program. We mentioned one caveat with these functions, and that is that millis() and micros() overflow after around 50 days and 70 minutes, respectively. Loop runs, and motorStop gets called. None. Along with this we also implement a simple code using a lastData variable and the millis() function to reset the counter back to zero in case there is no input for the last 10 seconds. begin (16, 2); } void loop () { sec = millis () / 1000; lcd. duration is the timespan during which the buzzer should stay on after the button was released. Arduino countdown LCD display code hour:minute:second format. e. If I wanted to make a sketch that won't lock up after 49-50 days because the millis() overflows. How to capture millisecond in arduino. So no sign of reset I guess ? @tmd3, I tried and it ran setup() only once at the beginning while my millis() still obviously resets all the time. print (sec); lcd. We can increment to the next melody: Like above, but we add the melody incrementing line in the if statement: current_melody = (current_melody + 1) % NR_MELODIES; We can stop playing: Here I would use the above if statement and set current_note to -1. Yes. Using Arduino Programming Questions. Arduino is in sleep so when I spray water on sensor I need to wait few seconds to wake up arduino and turn on powersuply on sensor Resetting a timer is, essentially, holding its value at zero. Okay I'm sure this is very simple but this is somehow escaping me. millis () time comes from the cycle counter. you may have to install the MsTimer2 library. 295 If millis() > 4294967295 then Arduino reset millis() counter to zero!!! "Reset the whole arduino!!" I figure this might work just because if the timer is not on I really don't care if it is resting itself or messing with millis(). Share. Button logic gets quite involved when using millis() to do things like debouncing , double click, press and hold and such. As others have said, read up on the BlinkWithoutDelay sketch. If we load this sketch onto our Arduino and. 8. Let's compare the two following inequations: millis() >= (previousMillis + TIME_INTERVAL) (millis. Which can be used to create a time base for various events in your applications (like LED blinking or whatever). Here is the variable declaration Arduino uses to persist millis: volatile unsigned long timer0_millis = 0; So I presume this is how I'd whack it, in my code: timer0_millis = 0;Implementing Multitasking with millis () Arduino Millis Example. Learning the software reset is a good thing if you are doing what I am doing. This will prevent your interval from being over 1 second on average, which is what would happen if you just stored the actual last read time in the variable. In addition, you can do so, specific code in different intervals. What you do is capture and save the value from into a variable. We can display up to 4 digits after the decimal. system January 9, 2013, 1:03pm 3. The quick answer to “How do you reset millis()” is: You Don’t! And here’s why: if you did, it would potentially break most libraries and functions that rely on it. Hey all, Pretty new to Arduino, and I'm having some trouble with using the millis() function. if millis() is near max, and time is less than millis() and (time + timeBetweenReading) rolls, it will repeatly trigger as long as millis() hasn't rolled. Wouldn't it be more useful if it gave the actual time of day? For example, you've designed a digital clock program and uploaded it to your Arduino.