![]() ![]() ![]() the way arduino implemented its timing functions, it tends to under-count, unless in an environment with other interrupts. delayMicroseconds() produced a delay of 45 ticks.it produced a delay of 77 ticks slightly worse than delay4us() t0delayus() is built up from timer0 delays.delay4us() is built up from NOP() it produced a delay of 65 ticks, or just over 4us.I used the following block to time the various approaches: time0=TCNT0 īefore that, I had reset the timer0 prescaler to 1:1 so each TCNT0 tick is 1/16th of a microsecond. It offers finer resolution plus accuracy. Use ticks, you can implement a clone of systick and use it as basis of the delay. You can change the prescaker to achieve 16th us resolution. If you need better resolution, micros () may be the way to go. Each is 4us as the prescaler is set to 64. Just like delay () has a microsecond-version called delayMicroseconds (), millis () has micros (). There are a few ways for short delays, each with its own shortfalls. The Arduino implementation is quite generic thus may not be as effective in some applications. Is there anything I can do to get correct, consistent results? It is worth noting that thisĬannot be achieved with digitalWrite(), as a call to this function Just add the missing time in a delay: noInterrupts() Īnd you have a cycle-accurate pulse width. Time it takes to execute the instruction that sets the port LOW. ![]() Makes a 0.125 µs long pulse (2 CPU cycles), because that's the (pin 19 on the Mega), I would proceed as follows. Note also that you have to block the interrupts if you want any kind ofĮdit: As an example, if I were to generate a 4 µs pulse on PD2 The main caveat is that the argument has toīe a compile-time constant. ![]() The AVR-libc is cycle-accurate and, for example _delay_us(1.125) ĭoes exactly what it says. They seem incredibly poor in accuracy/consistency and Im struggling to understand why. However, to answer your actual question, there is a more accurateĪlternative to delayMicroseconds(): the function _delay_us() from Im struggling to understand how the micros(), millis(), delay() and delaymicroseconds() work on the Arduino Zero. Code samples in the reference are released into the public domain.As explained in the previous answers, your actual problem is not theĪccuracy of delayMicroseconds(), but rather the resolution of The text of the Arduino reference is licensed under aĬreative Commons Attribution-ShareAlike 3.0 License. We cannot assure that delayMicroseconds will perform precisely for smaller delay-times.Īs of Arduino 0018, delayMicroseconds() no longer disables interrupts.Ĭorrections, suggestions, and new documentation should be posted to the Forum. This function works very accurately in the range 3 microseconds and up. It sends a train of pulses with 100 microseconds period. Click the tab to view its contents, including detailed descriptions of the available functions. When the IDE opens, notice that it automatically opens the 'Timer2Counter.ino' file with it, as a second tab. Click the 'Timer2CounterBasicExample.ino' file to open it in your Arduino IDE. PinMode(outPin, OUTPUT) // sets the digital pin as outputĭigitalWrite(outPin, HIGH) // sets the pin onĭelayMicroseconds(50) // pauses for 50 microsecondsĭigitalWrite(outPin, LOW) // sets the pin offĬonfigures pin number 8 to work as an output pin. Step 3: Open the Example File in Your Arduino IDE. Us: the number of microseconds to pause ( unsigned int) For delays longer than a few thousand microseconds, you should use delay() instead. This could change in future Arduino releases. There are a thousand microseconds in a millisecond, and a million microseconds in a second.Ĭurrently, the largest value that will produce an accurate delay is 16383. Pauses the program for the amount of time (in microseconds) specified as parameter. Reference Language | Libraries | Comparison | Changes ![]()
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