How to move a servo quickly and without delay function

Question

Im trying to move a servo from one place to another while using the typical for loop you find in the servo's library example:

int lightON = 180;
int lightOFF = 90;
for (pos1 = lightOFF; pos1 <= lightON; pos1 += 1) {
 servo1.write(pos1);
 delay(15);
}
for (pos1 = lightON; pos1 >= lightOFF; pos1 -= 1) {
 servo1.write(pos1);
 delay(15);
}

The thing is that while this does work, I want to be able to move the servo a little quicker, but I can't use the delay() function because of some connectivity issues with another library (BLYNK).

How could I move the servo from lightOFF to lightON the quickest way possible without using the delay() function?

Answer 1

The quickest way possible from LightON to LightOFF is simply servo1.write(lightOFF); without loops or delays, in one go; no need to do it degree by degree. For example:

int lightON = 180;
int lightOFF = 90;
for (pos1 = lightOFF; pos1 <= lightON; pos1++) {
 servo1.write(pos1);
 delay(15);
}
servo1.write(lightOFF);

If you want it to move a few degrees every loop and do other things in the loop while it moves, you can time it with millis() instead of delay(). The code below should move the servo 5 degrees every 0.5s:

int moveTime = 500; // Move every 0.5s
unsigned long int startMillis = 0;
int position = lightOFF;
int step = 5; // Move 5 degrees
void loop() {
 if (millis() - startMillis >= moveTime) {
 servo1.write(position);
 if (position <= lightON) {
 position = position + step;
 }
 startMillis = millis();
 }
 // Do other things
}

Untested and incomplete, but you get the idea.

Answer 2

The best way is to use map() function.

void loop() {
 unsigned long progress = millis() - startMillis;
 int angle = map(progress, 0, MOVING_PEDIOD, lightOFF , lightON);
 servo1.write(angle);
}

The above code use the millis() function, therefore you do not need to worry about blocking other code.

Full instruction is available on How to control speed of servo motor

• Edgar Bonet: Nice idea! It should be combined with constrain() in order to avoid overshooting (map() does not implicitly constrain()).