# Running servo for loop delay with separate pushbutton if statements **URL:** \ **Category:** Programming\ **Created:** [November 21, 2022, 12:48am UTC](https://forum.arduino.cc/t/running-servo-for-loop-delay-with-separate-pushbutton-if-statements/1056164 "2022-11-21T00:48:17Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![alwang123651](https://avatars.discourse-cdn.com/v4/letter/a/a88e4f/32.png) [@alwang123651](https://forum.arduino.cc/u/alwang123651)\ **Post date:** [November 21, 2022, 12:48am UTC](https://forum.arduino.cc/t/running-servo-for-loop-delay-with-separate-pushbutton-if-statements/1056164/1 "2022-11-21T00:48:17Z")
Hi all! I am a novice programmer trying to run tests cases in tandem with each other. The objective is to create one file with all tests cases on it so they can be tested one right after the other. I am currently testing the use of a pushbutton to turn an led on and off (test case 1) and a test to rotate a servo (test case 2). Both test cases work separately when I run them, however, having the servo test case active prevents the pushbutton test case from working. I found this to be because of a delay function used in the servo test which for some reason stops my pushbutton test case from working. When I remove the delay they both work fine but the servo spins like crazy which is not my desired output (I just want it to rotate fully back in forth in a smooth motion). Here is the code ```cpp Servo servo1; const int BUTTON_PIN = 2; const int LED_PIN = 3; byte lastButtonState = LOW; byte ledState = LOW; void setup() { servo1.attach(5); pinMode(BUTTON_PIN, INPUT); pinMode(LED_PIN, OUTPUT); } void loop() { //TEST CASE 1 //PUSHBUTTON byte buttonState = digitalRead(BUTTON_PIN); if (buttonState != lastButtonState) { lastButtonState = buttonState; if (buttonState == LOW) { ledState = (ledState == HIGH) ? LOW: HIGH; digitalWrite(LED_PIN, ledState); } } // TEST CASE 2 // SERVO for(int position = 0; position <= 180; position += 1){ servo1.write(position+5); delay(55); //THIS IS CREATING PROBLEMS } for(int position = 180; position >= 0; position -= 1){ servo1.write(position-5); delay(55); //THIS IS CREATING PROBLEMS } } ``` Is there some way I can get both test cases to run together? Any help would be greatly appreciated. ---
**Author:** ![gcjr](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/gcjr/32/314015_2.png) [@gcjr](https://forum.arduino.cc/u/gcjr)\ **Post date:** [November 21, 2022, 1:04am UTC](https://forum.arduino.cc/t/running-servo-for-loop-delay-with-separate-pushbutton-if-statements/1056164/2 "2022-11-21T01:04:17Z")
need to recognize a button press while the servo loop is running. the better approach is to use millis() instead of a delay. the following in/decrements the position each iteration using "dir" avoiding separate loops. add your servo, button and LED functions ```cpp unsigned long msecLst; const int Pos0 = 0; const int PosN = 180; int pos = Pos0; int dir = 1; void loop() { unsigned long msec = millis (); if (msec - msecLst >= 55) { pos += dir; Serial.println (pos); if (Pos0 == pos || PosN == pos) dir = -dir; } } void setup () { Serial.begin (9600); } ``` ---
**Author:** ![alwang123651](https://avatars.discourse-cdn.com/v4/letter/a/a88e4f/32.png) [@alwang123651](https://forum.arduino.cc/u/alwang123651)\ **Post date:** [November 21, 2022, 1:36am UTC](https://forum.arduino.cc/t/running-servo-for-loop-delay-with-separate-pushbutton-if-statements/1056164/3 "2022-11-21T01:36:53Z")
HI gcjr! Thank you for your reply! Are you saying that I can just directly implement this into my code without changing any of it? Or should I still remove the delays I have in my servo test case? ---
**Author:** ![gcjr](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/gcjr/32/314015_2.png) [@gcjr](https://forum.arduino.cc/u/gcjr)\ **Post date:** [November 21, 2022, 9:23am UTC](https://forum.arduino.cc/t/running-servo-for-loop-delay-with-separate-pushbutton-if-statements/1056164/4 "2022-11-21T09:23:09Z")
> [@alwang123651](#): > > Are you saying that I can just directly implement this into my code without changing any of it? you need to study, understand it and modify it to add your servo operations and LED test this is a timer based example. while this code is executed each iteration of loop(), the body of the if only executes every 55 msec givie it a shot and we can help ---
**Author:** ![StefanL38](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/stefanl38/32/713548_2.png) [@StefanL38](https://forum.arduino.cc/u/StefanL38)\ **Post date:** [November 21, 2022, 7:34pm UTC](https://forum.arduino.cc/t/running-servo-for-loop-delay-with-separate-pushbutton-if-statements/1056164/5 "2022-11-21T19:34:05Z")
> [@alwang123651](#): > > ```arduino > for(int position = 0; position <= 180; position += 1){ > // stay INSIDE this for-loop until the counting up from 0 to 180 has finished > // which needs 181 * 55 milliseconds = 9900 milliseconds = 9,9 seconds > servo1.write(position+5); > delay(55); //THIS IS CREATING PROBLEMS > } > for(int position = 180; position >= 0; position -= 1){ > // stay INSIDE this for-loop until the counting up from 0 to 180 has finished > // which needs 181 * 55 milliseconds = 9900 milliseconds = 9,9 seconds > servo1.write(position-5); > delay(55); //THIS IS CREATING PROBLEMS > } > > ``` This is code that is blocking. // stay INSIDE this for-loop until the counting up from 0 to 180 has finished // which needs 181 \* 55 milliseconds = 9900 milliseconds = 9,9 seconds To make the code responsive again that at the code is reacting on button-presses at **any** time requires **non** -blocking coding. The basic principle of non-blocking coding is - avoid all and any for-loops - avoid all and any while-loops - avoid all and any delay() - the only thing that is looping is void loop() **itself** - if code shall not be executed all the time the execution has to be made **conditional** with if-conditions or switch-case-break-statements. - to achieve the goal that parts of the code shall be only executed after some time **non** -blocking timing **must** be used. From this description you can see going beyond some small demo-programs requires quite some knowledge of more advanced programming-techniques Of course there are a lot of tutorials online for that. Most of them **really bad** in explaining. Some of them of medium quality but **don't** use everyday examples which would make it easier to understand. And in **very rare** cases easy to understand tutorials that use everyday examples (as analogons) to explain what the code does. Still the main thing is: understanding the **concepts** of - non-blocking timing - state-machines - looping through using of void loop() **combined** with using quickly\_\_\_ jump-in / jump-out functions This is not a trivial matter of 15 minutes. It is more of some hours with **very good** tutorials and it is a matter of **days** with medium quality tutorials. As a starting point give this tutorial about non-blocking timing a try > [@Example-code for timing based on millis() easier to understand through the use of example-numbers / avoiding delay()](https://forum.arduino.cc/t/example-code-for-timing-based-on-millis-easier-to-understand-through-the-use-of-example-numbers-avoiding-delay/974017): > > non-blocking timing. Execute code only from time to time. There are a lot of different ways to learn programming. This thread wants to add another approach that is different to the yet existing ones. UPDATE 06.01.2023 if you are mainly interested in applying non-blocking timing you can do a quick read of this short tutorial / demonstration If you are intersted in understanding the details how it works go on reading here. I use an everyday analogon in this post to explain the basic principle … best regards Stefan ---
**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\ **Post date:** [May 20, 2023, 7:34pm UTC](https://forum.arduino.cc/t/running-servo-for-loop-delay-with-separate-pushbutton-if-statements/1056164/6 "2023-05-20T19:34:52Z")
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