I've looked on lots of forums and have tried a few. When the counter reaches 3 set it back to zero. Once setup () is finished, Arduino calls the loop () method over and over again. millis() is incremented (for 16 MHz AVR chips and some others) every 1. That's the idea - the original poster wanted a timing pulse that reset every day to zero - the modulo (%) was one way to provide it. 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. At the start of each timing period print the value of the counter. Experimenting with an ATmega328P on a breadboard. update function. timer0_millis = 0; // reset millis, will eliminate this in future startTime = millis. Can it be reset to zero and started again within the same sketch? Yes it can, but why would you want to?Then check if more than our waiting time has passed. println (println = print line) function to print the value of millis. d=2000ms. Here is a small example sketch to show millis() since last reset in hh:mm:ss format. When the timing starts you store a timestamp a variable. It allows me to control RGB LED modules. millis () just uses Timer 0 overflow counts. วัดระดับน้ำแบบไร้สัมผัส รุ่น XKC-Y25-PNP ร่วมกับ Arduino Nano หรือ ESP32 เพื่อวัดระดับน้ำแบบไม่ต้องติดตั้งให้สัมผัส. 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. Arduino is always connected to battery without disconecting 24/7. 295 If millis() > 4294967295 then Arduino reset millis(). These last four options are achieved by various combinations of the RS1 and RS2 control bits. // fall through to. I somewhere heard that it could work even in power-save mode but thats not important for now. This can be done with the pressing reset button of Arduino. Number of milliseconds passed since the program started. millis () start counting when the CPU has pronounced its a live not when it starts running your code. The count is working well. The millis register is 4 bytes in width, so the largest unsigned number it can hold is: 11111111 11111111 11111111 11111111. If analogread bigger than 600, then digitalwrite 13, high. Do i need to reset CurrTime and StrobeTime to zero at the begining of the loop? Koepel December 14, 2022, 3:36pm 14. (go back to zero), after approximately 50 days. So 0-4294947296=20000 1000-4294947296=21000 2000-4294947296=22000 work is not interrupted,of course my limiter 60000 under my limiter condition. This code activates a relay (pin 5) if the flow count reaches 400 milliliters. 2: Last millis = 200, current millis = 44, elapsed = 44-200 = 100. print (millis ()) inside the loop to check the value of millis (), and realized that my millis () function was only returning zero. Syntax. For a simple project where two arduino devices (separately and remotely with the same sketch) don't begin until a user presses a button, I'm considering using "randomSeed(millis());" to reset my RNG for the sketch at a point after manual user-interaction in loop(). 1. millis () will wrap around to 0 after about 49 days (micros. The timer does not stop. 1 Answer. LMAO! Wawa November 21, 2018, 8:26pm 27. Please i would like to know does millis overflow (go back to zero), after approximately 50 days as i found here. The return value for millis() is of type unsigned long. Removing power also works. The issue is, if i need to interrupt the code at any moment, i have to wait a few seconds before it finally changes out of the condition. Reset the flag to false at the start of loop. It starts at 0 each time the board is reset and is incremented each millisecond by a CPU hardware counter. Global variables are initialized to zero and millis() starts at 0 so that is usually close enough. I found myself leveraging the Keypad library even when I only had one or two buttons. What you do is capture and save the value from into a variable. mondoha May 29, 2020, 1:12am 3. After more than a month arduino won't detect water even if sensor is in water all time. 1: Last millis = 100, current millis = 200, elapsed = 200-100 = 100. println (time); //prints time since program started delay (1000); // wait a second so. Majenko ♦. During that millisecond you will be toggling the LED on and off very fast. Here is a very simple example to show you millis() in action: /* millis() demonstration */Arduino: How to reset millis( )?Helpful? Please support me on Patreon: thanks & praise to God, and with thanks to. val = digitalRead (REED); The digitalRead () function returns an integer value equal to HIGH (1) or LOW (0). e. If it has a second microcontroller that it always on (like the Uno), you should find a way to disable it. When checking for elapsed time always use the construct "millis () - lastTimeChecked >= elapsed time". Reset the counter. Provide details and share your research! But avoid. 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. I think that I have problem when millis go back to zero. b707 November 22, 2023, 10:37pm 6. 10 months ago. long dly = millis (); while (millis () - dly < 250) { yield (); // enough time to send response } At line 1, you define a variable that holds time passed since start then inside the while loop you retrive the current millis () until it is greater than 250ms. 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. time = millis() Parameters. print (" "); } The board wasn't exiting the while loop, so I included serial. 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. Then in the loop we’re going to use the Serial. print (millis ()); Serial. Hi! Beginner here so pls bear with me. else, (we have not been up for at least an hour), print out the number of minutes we have been up. Hello, I have a library that I got off the internet. The actuators control a set of barn doors in my house. Preference and clarity might dictate you avoid using "lastMillis" or "previousMillis" as it's not the last millis () when you set it, but it becomes that, so your English teacher might suggest using "timeStamp" or "processGood" or something that means the same thing everywhere you use the term. b=500ms. 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. 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. Example,starttimex=4294947296. How can I format millis into a 24 hour display, [HH:MM:SS] that resets every 24 hours, or better yet, insert an authentic. I can't reach to the correct statements for the reset and where exactly to write these statements in the loop. Study the BlinkWithoutDelay example in the IDE. arduino programs are standalone programs without os. I've been experimenting different codes but to no avail. 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. That is not needed. 7. 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. The timer and interrupt timer allows you to perform an interrupt once per millisecond. int last = 0; int m = 0; void draw () {. Start by writing a small program using millis() for timing that increments a counter (starting at zero) each time the timing period ends. Let's say that we are interested in tracking a duration of 10. The return value for millis() is of type unsigned long, logic errors may occur if a programmer tries to do arithmetic with smaller data types such as int. The RESET button is a white or blue push button located on top of your Arduino board. Think hard about reply #2. 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). hw_timer_t * timerBegin(uint32_t frequency); frequency select timer frequency in Hz. As soon as I make power reset arduino again works great. changing the display layout (after lightning the display a series of short pushes) reseting the board when pushed for more than 5 seconds. 0 forces the compiler to see 1000 as a float value (you can also use 1000f if you prefer). " If you don't want the zero, then use %d instead of %02d. To state it another way, the value that is returned by the function millis () is the. Preference and clarity might dictate you avoid using "lastMillis" or "previousMillis" as it's not the last millis () when you set it, but it becomes that, so your English teacher might suggest using "timeStamp" or "processGood" or something that means the same thing everywhere you use the term. . Yes, but it is probably not what you want to do. Syntax. 7 day window) could be very hazardous, depending on how the time frames line up. I read somewhere that millis resets to zero and starts again which functionally does not affect the running of the program. It won't cause the Arduino to crash, lock-up, or anything like that, it'll just happen. If the sketch is intended to run for longer than that, It needs to make sure the rollover does not make the sketch fail. 71 days) the timer wraps round to zero and this is the Arduino millis overflow problem. Example 4: Controlling a Servo with Precise Timing. This is a basic code for countdown display in the format HH:MM: SS; Hour:Minute:Second. OS, IDE, and SDK. so, I want to press A2 to reset to 0. I think there is no need of disabling it. The Arduino has three timers – Timer0, Timer1, and Timer2. You don't reset millis(). 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. 999 Second day 86400000 = Uptime 1 days 00:00:00. My goal is to be able to have a few buttons (starting. So far I'm able to make everything work except for the timer to reset; once you let go of your bottle and light hits the LDR sensor the alarms continue to go off. print (millis ()); Serial. reset the count to zero when pin 7 is HIGH. 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 ();. I have a button, linked to pin 2 of my arduino, to execute my interrupt service routine. Nothing "bad" happens. From then on the code works fine. Hello, I have been working on a project and I recently started noticing some very strange behavior. In this case it will trigger when millis is at 5. , Case 1) when the A3 button is pushed. 367 2 7. 4. Let’s review some basic Arduino function jargon. 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. Hello, I have a library that I got off the internet. On 16 MHz Arduino boards (e. (It works when I remove those two but I added because I want the millis() to be reset to zero once it hits 70seconds). There are a few problems as I don't wish to reset millis() every time and I'm using a button rather than the boolean within the knock. g. A few ways, depending on your level of comfort: You can declare the stock Arduino Timer0 OVF "weak" and write your own where you can insert your ISR. Performing timepoint1 = millis(); near the overflow can (and will) result in erroneous interval comparisons if millis() returns back to zero. Please note that the return value for millis () is of type unsigned long, logic errors may occur if a programmer tries to do arithmetic with smaller data types such as int. Millis () does not back to zero after woke up from deep sleep mode. The Arduino programming language Reference, organized into Functions, Variable and Constant,. Parameters. My time flies!"); Reset (); Resets the timer to the current value of the millis timer. Arduino Stack Exchange is a question and answer site for developers of open-source hardware and software that is compatible with Arduino. It may have other features but it will always have these. the value returned is always a multiple of four). 000 End of first day = Uptime 0 days 23:59:59. Returns the number of milliseconds passed since the Arduino board began running the current program. ketika millis di baca maka millis akan. If you look at the source code for 'delay ()' you will see. To get the value of the counter at a particular juncture, just call the function – for example: start=millis(); Where start is an unsigned long variable. Returns the number of milliseconds passed since the Arduino board began running the current program. This leaves 155 that needs to be subtracted from the maximum value and 255 - 155 = 100. millis () is one of the fastest function of the Arduino core. Using board reset button that resets program & all values to it's start wont help. This number will overflow (go back to zero), after approximately 50 days. The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3. The Easy Fix Performing timepoint1 = millis(); near the overflow can (and will) result in erroneous interval comparisons if millis() returns back to zero. Which can be used to create a time base for various events in your applications (like LED blinking or whatever). More about millis () later. You are more interested in the difference. If I press a second time reset millis ( millis. Probably while loop on line 140 is done (remoteState >= 20): while (remoteState < 20) {. Returns. case1a: count three instances of something. The Arduino comes with three timers known as Timer0. When interrupts are back on, check that time against millis and if it's greater than. It does however turn out that functions like millis() and Serial() internal settings are determined at compile time. 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. This number will overflow (go back to zero), after. 0 License. How often do you reset the wall clock to midnight ? millis / micros work the same way… you don’t reset them. Use case statements for your LEDs. Subtract this variable from your current reading to get your "tared" Yaw value. Let's clear up some misconceptions: The processor does not reset when the timer overflows. tomstell July 9, 2019, 1:57pm 15. In addition, you can do so, specific code in different intervals. A beginners guide if you need more explanation. My guess is it will be about as deadly as the Millenium Bug turned out to be - but you won't find out until next year now. We mentioned one caveat with these functions, and that is that millis() and micros() overflow after around 50 days and 70 minutes, respectively. girishrajg May 5, 2021, 2:04pm 1. The reference guide tells me that millis () provides a value of data type unsigned long. 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. I've been experimenting different codes but to no avail. Because the only millis functions I have seen are for blinking leds but I don’t know how to apply it to my problem. I found a very simple but working code for this project. begin (9600); } void loop () { Serial. ,. When you have finished, subtract the recorded time from the current time, to find the elapsed time. Everywhere I read it says that millis its not reliable, and in a feel tests it seems not very accurate. c=1000ms. You set RS1 = 0 and RS2 = 0 (see page 13 of the datasheet you provided) and INTCN = 0 (page 9). and only wanted to perform the action once e. Perhaps it's named startTimestamp. Please note that the. This tells you the last time you saw some flow. The counter resets when the Arduino is reset, it reaches the maximum value or a new sketch is uploaded. Arduino Timer count resets at 65 but it should reset at 70. , Case 2 , Case 3 and Case 4) back to accessory mode(i. Returns the number of milliseconds since the Arduino board began running the current program. 1. It allows me to control RGB LED modules. Start by writing a small program using millis() for timing that increments a counter (starting at zero) each time the timing period ends. To connect the pulse sensor with the Arduino, first, connect the VCC pin of the sensor to the 5V pin on the Arduino and connect the GND pin of the sensor to. So if timebetweenReading is 5000 (five seconds) and the loop processes in 10 milliseconds, for the last five seconds of the fifty day period, the sensor will be read 1000ms/10ms = 100. I have written a simple code to read and write data via USB on Arduino Console from/to Arduino Zero (powered by external battery). You can reset millis by restarting the arduino. This number will overflow (go back to zero), after approximately 49 days. Raspberry Pi 40-pin Compatible GPIO. Here’s the circuit diagram for this example. It may help with understanding the technique. The millis feature of the Arduino Code allows the Arduino to display the functions up to the value in milliseconds to 100% accuracy. system December 18, 2018, 7:36am 1. For accurate timing over short intervals, consider using micros (). what I want to add A2 as A reset button. When that occurs take the required action (s) and save the value millis () again as the start of the. Here's original code: #include <Wire. Reconfiguration of the microcontroller’s timers may result in inaccurate millis() readings. Returns. The actuators are programmed to open and close with the push of a button (z-wave relay programmed as 6 second momentary switch). begin (9600); } void loop () { Serial. 999 Absolutely MAX millis() unsigned long is 4294967295 = Uptime 49 days 17:02:47. cc millis() - Arduino Reference. Is it bad your clock overflows (goes back to zero) at midnight? No it isn't. I'm hoping to build a simple irrigation system wherein 2 (with the idea to expand) momentary push buttons activate a relay (solenoid valve) and. If the flow stops before 400 milliliters is reached, what is needed to reset the pulse counter to. There is other stuff that is run if millis since last run is more than 100, like a LED pulse. I’ve read online that somebody is trying to reset the hardware timer for. A recorded timepoint1, compared to overflowed millis() will return nothing : difference = timepoint2 - timepoint1;. 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. println (println = print line) function to print the value of millis. h> #define SEALEVELPRESSURE_HPA (1013. And inPlayMetronome is an instance variable. 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 to count absolutely random logical pulses in speed up to 7000 counts per second (so basic 16bit counter should be fine. Then it tells me that an unsigned long (32 bits) ranges from 0 to 4,294,967,295 (2^32 - 1). So Im having a hardtime adding a code that puts the states(i. I guess that is a approach to reset the timer used by the millis () function. It simply appears to be held up by the VB serial reader, stuck in the Arduino and the millis counter stops for a bit. I want to calculate the trend of temperature, pressure and humidity. No, like this: unsigned long oldTime; unsigned long CalculateDeltaTime () { unsigned long TimeNow = millis (); unsigned long deltaTime = TimeNow - oldTime; oldTime = TimeNow; return deltaTime; } See it here in action. My time flies!"); Reset (); Resets the timer to the current value of the millis timer. Project Overview. millis () [Time] Description. 0 at the end of 1000. Hi all I don't use ardunio programming on a regular basis but am always dipping in and out which doesn't make things easy, I wanted to execute a program after a button press otherwise do nothing and wanted use millis() instead of delay. 024 KHz. jremington July 25, 2016, 4:13pm 2. Words have been provided as cluses so one can do research. christop July 12, 2023, 10:56pm 81. while (millis () < INTERVAL + currentMillis) {. For accurate timing over short intervals, consider using micros (). As others have said, read up on the BlinkWithoutDelay sketch. Hello everyone, I'm hoping you can help me with a problem I'm having with my Arduino project. If you have delay()s in a program as well as timing using millis() you may find that the millis() timing does not. jremington July 25, 2016, 4:13pm 2. 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. You can. ) When the result is 60,000 or bigger, there's yer minute. , Case 2 , Case 3 and Case 4) back to accessory mode(i. Using 16 bits of millis () you can time up to 65. Share. Pressing it has the same effect as disconnecting and reconnecting the power supply: The board will wait briefly for a new sketch to uploaded, then it will start executing any instructions in the sketch from the beginning. Code for the Arduino Digital Measuring Wheel. How would one internally to the arduino, reset the millis command. While the interrupts are off, check pulsecount. Timer0 is used to generate interrupts once every millisecond. change to arduino IDE and press Ctrl-V to insert the complete code directly into the arduino-IDE. The thing is, I wanted to control millis in a way that my arduino will only start counting when my pin 3 is HIGH. How can I format millis into a 24 hour display, [HH:MM:SS] that resets every 24 hours, or better yet, insert an authentic. BLOG# 4- BPM Uno – System Implementation and Testing. I will be unit testing the 2 maintimer=millis(); while (millis()-timer<=interval) { digitalWrite(pumpa, LOW); // activate pump relay } Your code is not good. You only have to access one RTC variable to do that. millis () is incremented (for 16 MHz AVR chips and some others) every 1. The actuators are programmed to open and close with the push of a button (z-wave relay programmed as 6 second momentary switch). Powering down the board. The type of Arduino I am using is: "Arduino Uno", and Arduino IDE Version is 1. arduino programs are standalone programs without os. I am trying to use its internal hardware counter in basic counter mode. The Easy FixNo. You can store the current time in a timeval struct variable with gettimeofday function on startup. But in the code, Timer 0 is disabled and so delay(), millis() etc won't work. 000 End of first day = Uptime 0 days 23:59:59. Just like your clock does. Reset is hale OK. 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. This drift is cumlative, i. You can't reset millis() unless you reset the processor. Short-circuit causing the processor to overheat then reset. println("10 seconds has passed. While millis() is the way to go with most things. If you find this number at startup, it is extremely likely that the program is starting from a warm reset. Continue begging for help. When you stop resetting the timer the value of millis () - yourTimer begins to increase. Hey all, Pretty new to Arduino, and I'm having some trouble with using the millis() function. Because, if millis is reset in loop,endtimex will be 0,1000,2000. The arduino reference for millis() says: "Returns the number of milliseconds passed since the Arduino board began running the current program. system January 25, 2012, 3:47pm #2. 32 KHz. The Arduino programming language Reference, organized into Functions, Variable and Constant, and Structure keywords. Arduino millis() Reset. Milis count the time since the program starts. So, for example, to get exact milliseconds, you'd target option 2, 1KHz. Check out delays are boring in our article 5 tips for Arduino programs to see why blocking code causes problems. time = millis() Parameters. 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. To use this library, open the Library Manager in the Arduino IDE and install it from there. If so, you don't need "timer0_millis", whatever that is. Blackfin: I think you can get what you ask by simply updating "startMillis" at each successful compare: void loop () { currentMillis = millis (); if (currentMillis -. The time is. When that while loop is finished, you are at the end of loop and then loop starts again from the beginning and eventually setting loopCounter back to 0 on line 137. Considering Arduino's. Hi there, kinda random question. It shouldn't reset millis() to 0 - it should just keep millis() from advancing while it's sleeping. I use this technique almost always. for (int s = 0; s < steps; s++) {. Author: Michael Contreras. and so you just get the first time millis is over 5000. I am assigning millis() to a long int and then printing the value and it is always 0! I think it has something to do with the library's timer and interrupt. But, my routine will run for years (I hope), and there is the remote, tiny possibility that someone initiates the routine right at the end of the millis() counter. When the right amount of time is selected with the press of the second button the countdown is started one sec at the time and it is displayed on the OLED screen. It starts at zero milliseconds each time the board is reset, and is incremented each millisecond by a CPU hardware counter. Programming is via a USBtinyISP. I used the 16-bit unsigned int in my millis_overdone. Note:. The use of millis() throughout this post is interchangeable with micros(). But I did not understand why Timer 0 is disabled. Expected max RPM is 3750. 192 KHz. A "running average" and "strikes per minute" are two completely different things. Some functions will not work while interrupts are disabled, and incoming communication may be ignored. print ("Seconds:"); lcd. I am trying to use its internal hardware counter in basic counter mode. Use the millis () Function to Check the Time Passed in Arduino. const byte interrupt_Pin = 2; //Sets the pin used for the. The RESET button is a white or blue push button located on top of your Arduino board. The "Arduino AVR Boards" and "Arduino megaAVR. However, if, at any time the state has changed (low->high or high->low) I want to reset the timer to zero and start over again. millis () will wrap around to 0 after about 49 days (micros. The millis () function gives you the time in milliseconds how long the arduino is already running (since the last power on). println (time); //prints time since program started delay (1000); // wait a second so. While input pin gets high for more than 10000 milli seconds output pin gets high. 2. Nothing "bad" happens. This number will overflow (go back to zero), after approximately 50 days. println ( millis () ); } Each time through the loop, this. In this case it will trigger when millis is at 5. How. The built-in Arduino function millis() returns the number of milliseconds since the Arduino was reset. The problem is that millis () is an unsigned long which goes from 0 up to 4,294,967,295 milliseconds, or about 49 days. e. h" and "TimeAlarms. Returns the number of milliseconds passed since the Arduino board began running the current program. e. 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. Let say i write an code analogRead. unsigned long time; void setup () { Serial. The project is about capturing the timestamp (in ms resolution) whenever something is crossing ultrasonic proximity sensor. It updates the counter, which is sent to the millis() function. 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. With a 16MHz system clock, the two LEDs stay in sync indefinitely. . Any help appreciated const int ledPin = 13; // the number of the LED pin long. then put a zero at the left to make it two digits. Code samples in the. const byte interrupt_Pin = 2; //Sets the pin used for the. Reset is hale OK. print ("Time: "); time = millis (); Serial. I somehow want to generate a "running average" over a minute so I can produce a "strikes per minute" value. Yield processing to other threads through the yield () weak symbol. Loop runs, and motorStop gets called. Only for you instead of telling a LED to turn on or off you'll call your print lines instead. If this value is TRUE the next time through loop(), I deal with the overflow and reset to false. Then we need to check in our first if statement, if current_note is not -1:Try the updated code. How. debouncing an interrupt trigger. Using millis() to decide when to make the only call to this code in a single "wrap" of millis (a specific 49.