Viewed 4k times. The problem is that as of now the hardware is removing a few milliseconds on the delay and so the time in the server ends up being p. Não é possível assegurar que delayMicroseconds() irá funcionar corretamente para valores menores. how can i re write this in millis so that its non-blocking i did the top part but i dont know what to do with the delaymicroseconds? unsigned long WaterWait = 4000; unsigned long Waterdelay =0; int trig = 12; int echo. I want to make a task that constructs and sends infrared commands. Download SafeString from the Arduino Library manager or from its zip file. //delay_us (us); // for the 16. I've seen arduino only accepts delayMicroseconds( a ), where a is an integer and a>=1. On the boards from the Arduino Portenta family this function has a resolution of one microsecond on all cores. */ void delayMicroseconds (unsigned int us) { // calling avrlib's delay_us () function with low values (e. Erfahrene Programmierer vermeiden normalerweise die Verwendung von delay () für das Timing von Ereignissen, die länger als 10 Millisekunden sind, es sei denn, der Arduino-Sketch ist sehr einfach. For accurate delays you need to turn off interrupts and can use avrlibc delays _delay_loop_1 executes three CPU cycles per iteration, not including the overhead the compiler needs to setup the. Corrections, suggestions, and new documentation are very welcomed. Description. It will be called regularly. The Full code Listing. void setup () {. Hi all, Being aware of the following bug with micros() function in ESP32 arduino, I have jumped into the FOCutils. Ex: delay(3 * 60 * 1000); will make the program sleep for 3 minutes. Currently, the largest value that will produce an accurate delay is 16383. Arduino: What is the difference between delay() and delaymicroseconds()Helpful? Please support me on Patreon: than. delayMicroseconds() does not use any counter, so it will work as normal. Duemilanove and Nano), this function has a resolution of four microseconds (i. 10:50:30. Và cứ mỗi 1000000 micro giây = 1 giây. Serial communication that appears. บอร์ด Arduino Uno R3 . There are a thousand microseconds in a millisecond, and a million microseconds in a second. delayMicroseconds () incorrect. 2. There are a thousand microseconds in a millisecond, and a million microseconds in a second. There are a thousand microseconds in a millisecond, and a million microseconds in a second. TWO - a blocking delay, but one that does NOT use timers (timer0, timer1, or timer2) and is able to work with libraries which have a lot of timing issues or which corrupt millis() or timer0 counts. This could change in future Arduino releases. 1. I guess the system timer runs with a resolution of 1 ms. The Arduino can count and measure time by utilizing the micros () or millis () functions. Diese Zahl läuft nach ca. If the time A sends the signal is TSA,; the time. 現在、正確な遅延. Click the "Timer2_Counter_Basic_Example. sleep is the time to delay in seconds (not milliseconds). MartinL October 22, 2015, 8:47am 2. The delayMicroseconds () function will provide accurate delays as may be needed for some types of applications (e. Description. B. However Delaymicroseconds() does not use the time interrupt As you may know once an interrupt is called it stops all other interrupts So the real. delayMicroseconds関数 delayMicroseconds関数は指定した時間(μs)プログラムを止めます。 使用例 Arduino IDEで使用するdelay関数の使い方は以下の通りです。 試しにこのプログラムをArduino UNOで実行すると、13ピンのLEDが蛍の様に不規則に明るさが変化します。 10. 6. Supports: periodic task execution (with dynamic execution period in milliseconds or microseconds – frequency of execution), number of iterations (limited or infinite number of iterations), execution of tasks in predefined sequence, dynamic change. cpp file. I mark it in the neighborhood of about 6 microseconds. For 50% you could enter the 512 directly. Among the functions available to it, the following can be highlighted: Scheduled execution every x milliseconds and even microseconds. It doesn't use timer0 like the AVR Arduinos, so you won't mess up these functions by using any of the timers. There are 1,000 microseconds in one millisecond, and 1 million microseconds in one second. g. I'm messing around with the following code: #define cyclespermicro 240 #define microcycles (n) (n*cyclespermicro) uint32_t startCounter, counter, cpu_cycles; int. There are a thousand microseconds in a millisecond and a million microseconds in a second. delayMicroseconds () deaktiviert ab Arduino 0018 keine Interrupts mehr. Using Arduino. delayMicroseconds limitation. This could change in future Arduino releases. Arduino Stack Exchange is a question and answer site for developers of open-source hardware and software that is compatible with Arduino. {"payload":{"allShortcutsEnabled":false,"fileTree":{"cores/arduino":{"items":[{"name":"USB","path":"cores/arduino/USB","contentType":"directory"},{"name":"compact. 4. 6 version, not when using alpha1 or latest master version of the core. delayMicroseconds() you can provide a number of microseconds to sleep. Some interesting info about delayMicroseconds(). Duemilanove and Nano), this function has a resolution of four microseconds (i. Currently, the largest value that will produce an accurate delay is 16383. Here is the code I am using:. 32 KHz. Certain things do go on while the delay () function is controlling the Atmega chip, however, because the delay function does not disable interrupts. Posts: 4689. The prototype modules of spectrometers were driven by an Arduino controller. The drawback you get when using micros () is that the time variable overflows. Programming Questions. I'm weighing two options for the software side of things - controlling the speed via DelayMicroseconds (as I've done using the borrowed code posted here) or learning to use the AccelStepper library. We are delaying here to make sure, that the HC. hw_timer_t * timerBegin(uint32_t frequency); frequency select timer frequency in Hz. There are a thousand. The minimum duration for delay() is 1 millisecond, so if you need to sleep for only 400 microseconds, here you have a new solution. Pauses the program for the amount of time (in microseconds) specified as parameter. Anmerkungen und Warnungen. The ROM function ets_delay_us() (defined in rom/ets_sys. 3. So I'm trying to create an energy meter device which will read power every minute and then send it every 5 minutes through a LoRa server, using an MKR 1300 arduino. The delayMicroseconds function, on the other hand, does not yield to other tasks, so using it for delays more than 20 milliseconds is not recommended. Making statements based on opinion; back them up with references or personal experience. ) to perform the delay. Begin calling the function. You can easily find or write a piece of code that delays for 12500 nanoseconds (+/-62. The sensor has 4 pins. 1 and arduino-0022 give me 1. delayMicroseconds (us)에 대하여 살펴보겠습니다. Arduino cuenta con un conjunto básico de funciones para el manejo de tiempo, y estas son: millis, micros, delay y delayMicroseconds. 125); does exactly what it says. delay (5) = 100 Hz at flow computer. If the ISR is getting executed during your measurement, then the execution time of the ISR will. startMicros = currentMicros; } Since there is nothing that can block it, it will always execute very fast. This could change in future Arduino releases. 1밀리초는 1000 마이크로 초, 1초는 100만 마이크로 초. 아두이노 0018 현재, delayMicroseconds() 는 더이상 인터럽트를 비활성화 하지 않는다. When the chosen time has passed the timer interrupt triggers, and you use that interrupt to turn on your output. There are a thousand microseconds in a millisecond, and a million microseconds in a second. Ask Question Asked 2 years, 10 months ago. arduino-nano. cpp file and seen that the bug is probably called :frowning: The bug is explained here: Hi all, Being aware of the following bug with micros() function in ESP32 arduino, I have jumped into the FOCutils. Certain things do go on while the delay () function is controlling the Atmega chip however, because the delay function does not disable interrupts. If you need better resolution, micros() may be the way to go. The delay has to be configurable to sub microsecond resolution. However, be aware that micros() will overflow after approximately 70 minutes, compared to millis()‘s 50 days. range e. For very precise delays, you can use delayMicroseconds(), up to 16383 us. I need something “delayMicroseconds( delay )” in Arduino. The Arduino Reference text is licensed under a Creative Commons Attribution-Share Alike 3. delayMicroseconds () deaktiviert ab Arduino 0018 keine Interrupts mehr. Description. Description. Currently, the largest value that will produce an accurate delay is 16383. Returns the number of microseconds since the Arduino board began running the current program. As of Arduino 0018, delayMicroseconds() no. delay ()함수의 매개변수는 ms로 1/1,000 초였죠. millis () is incremented (for 16 MHz AVR chips and some others) every 1. Forum 2005-2010 (read only) Software Bugs & Suggestions. I have downloaded board files into Arduino to enable me to program the attiny 25/45/85/chips at 1Mhz or 8Mhz. Note that some manufactures do not follow this. g. Currently, the largest value that will produce an accurate delay is 16383. Não é possível assegurar que delayMicroseconds () irá funcionar corretamente para valores menores. This page is also. 13+) 6th Jan 2020 update: The millisDelay class is now part of the SafeString library V3+. delay() is a blocking function. Blink without Delay - Arduino Tutorial. 967295 microSeconds. g. can anyone help me debug this code my delay microseconds is not working and my servo write for 180 as well. I use two OLIMEXINO 85 to implement a 2 channel remote control and control 2 digital servos. You set RS1 = 0 and RS2 = 0 (see page 13 of the datasheet you provided) and INTCN = 0 (page 9). Click the tab to view its contents, including detailed descriptions of the available functions. Timing chart for signal input and output for micro-spectrometer Hamamatsu. Hello everyone, I have the following code that I'm using to accelerate, decelerate while rotating a stepper motor. Super Contributor. The inverse of that. Because a delay inside an interrupt causes that interrupt and other (lower priority) interrupts not to execute anymore until the delay is over. Such that I can input the frequency and duty cycle and read it with an oscilloscope. Description. Currently, the largest value that will produce an accurate delay is 16383; larger values can produce an extremely short delay. Description. Currently, the largest value that will produce an accurate delay is 16383. 8. Hello everyone, I am having an issue here regarding delays and float values. For delays longer than a few thousand microseconds, you should use delay () instead. 5%. For my project I need to measure time in nanosecond fineness. digiatlWrite (pin. It is commonly used in obstacle avoiding robots and automation projects. 001); a. :The delay () function will make the Arduino stop until your specified interval has expired. ) Casting that result to an unsigned long doesn't get you 60000 back. This function works very accurately in the range 3 microseconds and up. 반환. To make sure variables shared between an ISR and the main program are updated correctly, declare them as volatile . So, for example, to get exact milliseconds, you'd target option 2, 1KHz. So, I've noticed that when ever I have a situation such that: delayMicroseconds(0), the actual delay turns out to be 16383µs. Well, I have a problem with my arduino DUE, I would like to do a delay of 100ns minimum, my code is very very very simple, only an interrupt of my pin 2 and I activate my pin 3. Take the number of minutes, multiply it by 60 to get the number of seconds, and then multiply it by 1000 to get the number of milliseconds. Currently, the largest value that will produce an accurate delay is 16383. Furthermore, the delayMicroseconds() function in Arduino is implemented through cycle-counting, but the millisecond-delay function is simply a busy. 024 KHz. This could change in future Arduino releases. This could change in future Arduino releases. Arrch July 31, 2012, 9:44pm 2. Pauses the program for the amount of time (in microseconds) specified as parameter. Read part 1. Attach the GND pin of the HC-SR04 to one of the GND pins on the Arduino. From delayMicroseconds() - Arduino Reference. The Uno's clock is a ceramic oscillator, with an accuracy on the order of +/- 0. They use the same 3 wire connector, ground. Before we overflow (about 71 minutes and. The micros () function counts in microseconds, which is a lot smaller than milliseconds, and it repeats every 70 minutes. Description. We can also use variables in the delay function. doesn't work with delays <1 ms. . . Software library: non, sending HIGH and LOW in between delayMicroseconds (100) ISR: not using interrupts, not using Serial. For a more complete version that can handle various clock frequencies, see the delayMicroseconds() function from the Arduino AVR core. So, since (by reading the link) we also. The main caveat is that the argument has to be a compile-time constant. Beschreibung. For delays longer than a few thousand. 👉 Complete Arduino Course for Beginner. Language. The delay function seems to be based on system ticks so that the delay time can be used for other tasks. If you add a delay in the ISR, and the buffer of the UART gets full, it will overflow and you miss bytes. So, if you don't compile your sketch specifying the correct board (but I have compiled it for the right board , the tiny85 running at 1Mhz or I have the option of choozing 8 Mhz both of which have the correct board. Even a simple loop causes it to crash: ELF file SHA256: 0000000000000000 Backtrace: 0x4008860c:0x3ffbf8f0 0x40088889:0x3ffbf910. This number represents the time in milliseconds the program has to wait until moving on to the next line of code. The interval is specified in microseconds, which may be an integer or floating point number, for more highly precise timing. 71 days. This function will return timer structure if configuration is successful. The Arduino programming language Reference, organized into Functions, Variable and Constant, and Structure keywords. We are delaying here to make sure, that the HC. I'm struggling to understand how the micros(), millis(), delay() and delaymicroseconds() work on the Arduino Zero. . Servos have integrated gears and a shaft that can be precisely controlled. Ideally, 500ns or less. g. digiatlWrite (pin. False is returned if all hardware resources are busy, used by other IntervalTimer objects. The first delay of 2us is to make sure we are at an established LOW level on the trigger pin, since the pin might have been HIGH before that. Asking for help, clarification, or responding to other answers. TWO - a blocking delay, but one that does NOT use timers (timer0, timer1, or timer2) and is able to work with libraries which have a lot of timing issues or which corrupt millis() or timer0 counts. 2. Serial communication that. I have been working on an LED controller that uses a Return-to-zero protocol that requires me to send high and low signals at delays of 0. Still, interrupts (e. There are a thousand microseconds in a millisecond, and a million microseconds in a second. delayMicroseconds () is a cycle-counting loop, so it doesn't include any time taken by background functions like interrupts. myTimer. Arduino millis () Function. Currently, the largest value that will produce an accurate delay is 16383. The delay function seems to be based on system ticks so that the delay time can be used for other tasks. 이 함수는 3 마이크로 초 이상 범위에서 매우 정확하게 돌아간다. This number will overflow (go back to zero), after approximately 70 minutes. Your stepX () function looks like this: void stepX () { currentMicros = micros (); // conditionally do some stuff. How it works. There are a thousand microseconds in a millisecond, and a million. 0. 11us per degree. delayMicroseconds() Description. } blocks the loop. From the arduino reference page for delay the parameter for delay is an unsigned long. A partir da versão Arduino 0018, delayMicroseconds () não mais desativa interrupções. Step 3: Open the Example File in Your Arduino IDE. These might take too long to complete, which will delay all other interrupts and code execution. I did not find any resource mentioning. Basically, I found out that delayMicroseconds(x) delays (on Arduino UNO, 16MHz) 7 Clock cycles for (x = 0, 1) 14 Clock cycles Short for (x >= 2) I noticed a too quick delay on 'x = 2' case. unsigned long startMillis = millis (); while (millis () - startMillis < LONG_DELAY_MS); This will delay up to approx. . So, you have to do something more like: for ( n = 1; n< 50; n++ ) { digitalWrite (pin, HIGH ); delayMicroseconds ( 2000 ); // send a 2ms pulse. We need to provide the HC-SR04 with a fitting trigger signal. Prescaler divides the Timer clock further, by the value that you input in the prescaler. This could change in future Arduino releases. Jumper wires. import cc. It seems like the program skips the command altogether. It covers non-blocking delays, non-blocking serial output, non-blocking user input, removing delays from third party libraries, and loop timers, so you can see and adjust the response/latency of your tasks. If I take 64 readings with a 1ms interval for stability that's 64 milliseconds. This feature can be used to build a plethora of fun audio projects, but also work as professional lab equipment as a cheap function generator, for example. Looking at the implementation of micros() and delayMicroseconds(), it is clear they have too much overhead. The input of the delayMicroseonds () function is an unsigned integer, and the maximum number that we. long duration; digitalWrite (trigger, LOW); delayMicroseconds (2); digitalWrite (trigger, HIGH); delayMicroseconds (10); digitalWrite (trigger, LOW); duration = pulseIn (echo, HIGH); distance = (duration/2) / 29. Switch to “Standby” mode, when you are not executing any task, which will allow us to save energy. Arduino에서 delayMicroseconds () 함수를 사용하여 마이크로초 단위로 지연을 추가할 수 있습니다. 19us pulses. Hi all, I'm a new member. Guide Home. See full list on deepbluembedded. g. delay (1000) - means delay of 1 sec. But for some reason Timer0 is being disabled, and can't use the delay(), millis() and delayMicroseconds(). I have figured out the timings and without Freertos it works. I discovered this experimenting with a sound synthesis program with a variable for the. Simplified for the 16 MHz boards: void delayMicroseconds(unsigned int us) { // for the 16 MHz clock on most Arduino boards // for a one-microsecond delay, simply return. digitalWrite (2, 0); pause (0. micro phải <= 16383. Certain things do go on while the delay () function is controlling the Atmega chip however, because the delay function does not disable interrupts. I have been working on an LED controller that uses a Return-to-zero protocol that requires me to send high and low signals at delays of 0. Don't delay more than 500 µs or so, or you'll miss a timer overflow. Raising the level, the interrupt handler can reduce the timer processing delay. 2. Currently, the largest value that will produce an accurate delay is 16383; larger values can produce an extremely short delay. 0592MHz with the Arduino environment. A typical servo uses 1500 microseconds as a center position signal. millis () will wrap around to 0 after about 49 days (micros. I would like to toggle an output pin in the order of microseconds so use the function delayMicroseconds. More knowledgeable programmers usually avoid the use of delay () for timing of events longer than 10’s of milliseconds unless the Arduino sketch is very simple. e. priority (number);AUTHOR: Jacob Hylén. Hi everyone! I want to implement a timing delay of 1us in my program. delayMicroseconds(50); // pauses for 50 microseconds. Serial communication that appears. Wir können nicht garantieren, dass delayMicroseconds () genau für kürzere Verzögerungszeiten funktionieren. The micros () function returns the number of microseconds from the time, the Arduino board begins running the current program. You could hand-code the delay. Auf 16-MHz-Arduino-Boards (z. It’s also one of the worst things. 5 microsecond wide pulse every 249. One could strip off using the Arduino core code and use the ESP32's API to read the A:D and strip off some computing time. For delays longer than a few thousand. Nothing discussed actually creates a pulse tho. 0. L16-R miniature linear servos are a big brother to the L12-R line. More knowledgeable programmers usually avoid the use of delay () for timing of events longer than 10’s of milliseconds unless the Arduino sketch is very simple. This could change in future Arduino releases. . The arduino-esp32 core achieves this using the following code for the delayMicroseconds() func. This function works very accurately in the range 3 microseconds and up. The issue is that the Labview will work randomly. Não é possível assegurar que delayMicroseconds () irá funcionar corretamente para valores menores. 3 did NOT have any type of guaranteed resolution whatsoever. 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. There are a thousand microseconds in a millisecond, and a million microseconds in a second. What version gives 4us then? [edit: Arduino 1. 19us as well]The Arduino Servo class keeps sending the last pulse every 20ms. Returns the number of microseconds since the Arduino board began running the current program. This number will overflow (go back to zero), after approximately 70 minutes. This number will overflow (go back to zero), after approximately 70 minutes. cpp 📋 Copy to clipboard ⇓ Download. 050. 015% will be difficult to meet. First divide by 1000 for the seconds, then by 60 for the minutes then by 60 for the hours then by 24 for the days = ~ 49. These last four options are achieved by various combinations of the RS1 and RS2 control bits. Jan 3, 2021. The real time clock method is the most accurate way but otherwise use millis. With Arduino you can do this with the millis () function, but that resets (overflow) every 16666 milliseconds. For the 2 microsecond delay, you'll probably spend more time looping around than you'll save. All good so far, using the delay command I can read frequencies up to 494 Hz, with the delay 1 microseconds. There is a lot of code in Arduino which looks like this: uint32_t start = micros(); while (!condition && micros() - start < timeout). Con số này là mức tối đa của hệ thống Arduino, và có thể sẽ. 2 - 330-560 Ohm resistors, for LEDs. I am using an UNO for my project. On 16 MHz Arduino boards (e. For accurate timing over short intervals, consider using micros (). Currently, the largest value that will produce an accurate delay is 16383. 5%. In most examples you need to use delay techniques in the java environment but these all operate on the order of milliseconds (1000 microseconds). Using millis() instead of. Internally, esp_timer uses a 64-bit hardware timer, where the implementation depends on the target. Still, interrupts (e. I really don’t know how the Arduino IDE did compile that succesfully… In the meantime, add. delayMicroseconds (0) delays far longer than expected. On 16 MHz Arduino boards (e. uint16_t and uint32_t (the same as unsigned long onHowever, there’s a big problem: its maximum size ends up being too small for long-term programs! To see how that works, consider: the largest value that micros () can produce is 2^32-1, or 4,294,967,295. The Arduino delayMicroseconds() function. When you call delay, it keeps the timer running sending pulses during the wait. void setup () { Serial. All without using the delay() function. This function works very accurately in the range 3 microseconds and up. ollie1400 pushed a commit to ollie1400/Arduino that referenced this issue on May 2, 2022. Standard servos allow the shaft to be positioned at various angles, usually between 0 and 180 degrees. 1ミリ秒以上. Currently, the largest value that will produce an accurate. arduino-nano. every 250 microseconds- closest 'delay' values I can get are delayMicroseconds(3), and (83) off, gives a 7. Anmerkungen und Warnungen. This is the second part of a series of ESP-IDF tutorials that I will complete as I learn stuff. 5 Hz one “cycle” takes 17391304,34 ns. So, if you don't compile your sketch specifying the correct board (but I have compiled it for the right board , the tiny85 running at 1Mhz or I have the option of choozing 8 Mhz both of which have the correct board. Essa função funciona bastante precisamente para valores maiores que 3 microssegundos. I've tried usleep and nanosleep but regadless of values they both last at least 100us! - measured using gettimeofday before and after. e esp_timer_get_time() return a int64_t value and is parsed as uint32_t in delayMicroseconds(). The High Resolution Timer (ESP Timer) provided by FreeRTOS uses a 64 bit hardware timer. In the tests I made at home, DUE gave an accuracy of +- 1 us and a stable time measurement. Documentation on this site suggests DelayMicroseconds is accurate down to 3 microseconds, which is more than enough accuracy for this project. You can either decrease the delay time between each step or you can adjust the size of the step the motor takes. For a normal Arduino @16MHz only the following code will be compiled: /* Delay for the given number of microseconds. It has a time limit of approximately 50 days, after this time, it will overflow and go back to zero. The difference between micros and millis is that, the micros() will overflow after approximately 70 minutes, compared to millis() which is 50 days. Recent versions of the Arduino IDE/Core for AVR do Link Time Optimization, which means that calls to delayMicroseconds() where the argument is constant are likely to be optimized to the point where they become significantly inaccurate fo. This may change in future Arduino. When you multiply the 16-bit signed integers 60 and 1000, you don't get 60000, but rather -5536. The Arduino UNO R4 Minima has a built in DAC (Digital-to-analog Converter) which is used to transform a digital signal to an analog one. Assumes a 8 or 16 MHz clock. 매개변수에 지정된 시간 (마이크로 초)동안 프로그램을 멈춘다. digitalWrite (2, 1); pause (0. pinMode (outPin, OUTPUT); // sets the digital pin as output. There are a thousand microseconds in a millisecond, and a million microseconds in a second. The delayMicroseconds () won't let me control multiple lamps, so I want to replace it with micros () (code below). With delayMicroseconds() you can provide a number of microseconds to sleep. The Arduino programming language Reference, organized into Functions, Variable and Constant, and Structure keywords. There are a thousand microseconds in a millisecond, and a million microseconds in a second. do the other actions. Just Copy and Paste this code in Arduino IDE Software and compile and upload to arduino board. How do I get millisecond and microsecond-resolution timestamps in Python? I'd also like the Arduino-like delay() (which delays in milliseconds) and delayMicroseconds() functions. . They seem incredibly poor in accuracy/consistency and I'm struggling to understand why. You will need: Arduino. There are a thousand microseconds in a millisecond, and a million microseconds in a second. 0 License. micro có kiểu dữ liệu là unsigned int. While refference page for delayMicroseconds states "the largest value that will produce an accurate delay is 16383", I found that any value over 1950 gives VERY inaccurate results. The maximum value it can take is 4,294,967,295 or 49 days. There are a thousand microseconds in a millisecond, and a million microseconds in a second. delayMicroseconds() works in arduino. On standard servos a parameter value of 1000 is fully counter-clockwise, 2000 is fully clockwise, and 1500 is in the middle. Better idea is, when caller will calculate before calling delayMicroseconds () or duplicate the bit-banging routines for two (or more) different clock speeds. No entanto, certas coisas continuam a acontecer enquanto a função delay () está controlando o microcontrolador, porque a função delay não desativa. This has since been fixed in the Arduino core and delayMicroseconds() appears to work correctly at 1 MHz w/ Arduino 1. There are a thousand microseconds in a millisecond, and a million microseconds in a second. 1. Another advantage of not using delay() or delayMicroseconds() is that with the technique in the tutorial your code will automatically start every sample after 200 µsecs regardless of how long the. We cannot assure that delayMicroseconds will perform precisely for smaller delay-times.