12/12/2023 0 Comments Arduino delay timelet it run from one hour, one day, and check how much drift you're getting. Your application might not require too much precision, and you could simply write a sketch to print the time every second on the serial. Like your watch needs to be readjusted from time to time.Īnother factor that affects accuracy, including for RTCs using a 32.768KHz crystal, is the temperature. Those variations on the frequency source will produce some drift over time. It also might be from good quartz crystal, with up to 0.001% accuracy. The main clock on your board might be generated by a ceramic resonator, which is not very accurate: around 0.5%-1% error. The time you refer, in this case "millis()" I believe, is maintained from a timer interrupt, which is derived from the main clock (normally 16Mhz). There are multiple versions and "clones" of the Arduino, and each one will probably use different components. A clock chip however (usually) has a battery backup, and will "know the time" once the power comes back on. Something to consider if you try to make do with the internal clock is: what happens if the power goes off? Then it loses track of when to turn the lights on and off. If you want super accuracy (sounds like you don't) then connecting up a GPS module lets you query the exact time from the satellite, which could cut the error down to negligible amounts. For example, if you delay for an hour, and then do something, make sure that the "do something" isn't added to the next delay time. I suggest you follow Chris Stratton's suggestion and code so that errors are not cumulative. Using the internal clock probably won't be as accurate, but could be OK in this case. Even for taking the temperature, a few minutes out when logging a reading is probably not going to matter. This would be an acceptable error for something like turning garden lights on and off. It is now about 3 years later, and it is running about 11 minutes slow. I don't recall ever resetting the clock on it. It uses a RTC chip (DS1307) which you can buy on eBay for $1 if not less. The user can switch between Celsius and Fahrenheit with a press of a button.I made a temperature and humidity sensor in August 2013. You have your microcontroller connected to a temperature sensor and an LCD screen, it records the temperature and writes it to the screen every 1 second. Let’s create an imaginary device to highlight this issue. So if delays block program execution, what can we do? Is there a way to make our delays non-blocking? An example of how this can go wrong ![]() As a result, using too many delays can ruin user experience, can make your device sluggish or can even cause it to lock up completely. Many Arduino libraries just blocking program execution without concern for what else the developer wants to do in that time. So if they are necessary, what’s the problem? The issue is how they implemented. ![]() For example, it’s not uncommon for an LCD or OLED display to require a millisecond or two to clear the data on the screen. This tells you that device needs some propagation time between clock pulses, or instructions, or whatever the case may be. If you read the datasheet for a given digital device requiring complex timing, you’ll often see a timing diagram. Some are applied appropriately, but not all. ![]() How to delay without pausing your programĭelays are used everywhere in Arduino.
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