Last Updated: 20/04/2024
#82 Servo Speed Control with millis()
Components >> #82 Servo Speed Control with millis()
Servo speed control using millis()
I often see beginners struggling to combine servos with other code because the normal servo examples us delay() and so block any other code while running.
I usually use the PCA9685 board for servo control, however for this tutorial I will use the Servo library and showe how it is possible to run multiple servos at different speeds and directions at the same time.
Servo Circuit
If you are just using a single servo you can use the Arduino 5v Supply. However the Arduino will struggle to power more than a single servo so a seperate 5v supply is required as shown below.
For the example code I used pins 8, 9 and 10.
Although the examples are based on an Arduino UNO, a Nano or Mega 2560 will also work without any modifications to the code.
Example 1: millisServoV1.ino
Click to Download code: millisServoV1.ino
This sketch controls a single servo, passing it random positions to move to at random speeds.
/* millisServoV1
20/04/2024
*/
#include
Servo servo1; // create servo object to control a servo
//This will store the data for servo1
unsigned int servo1Data[3];//moveTo, currentPos, speed
unsigned long servo1millis;
unsigned long currentMillis;//Holds the current board time in milliseconds
void setup() {
Serial.begin(9600);
Serial.println("millisServoV1");
servo1.attach(8); // attaches the servo on pin 9 to the servo object
}
void loop() {
int servoFinished;
currentMillis = millis();
servoFinished = servo1Control();//controls servo 1
if(servoFinished < 1){//If 0 is returned the servo has reached it's destination
servo1Data[0] = random(179); //pick a random angle between 0 - 179
servo1Data[2] = random(1,100); // pick a random speed between 1 and 100...speed in milliseconds per degree moved
Serial.print("Servo 1 Next Pos: ");
Serial.print(servo1Data[0]);
Serial.print(" Servo 1 Next Speed: ");
Serial.println(servo1Data[2]);
}
}
int servo1Control(){
int returnPos;
returnPos = 0;//return 0 if reached destination
if(servo1Data[0] > 179){
servo1Data[0] = 179;//limit check in case soeone tried to move servo more than 179 degrees
}
if(servo1Data[0] != servo1Data[1]){//is there still a distance to move
if(currentMillis - servo1millis >= servo1Data[2]){//is it time to move
servo1millis = currentMillis;
if(servo1Data[0] > servo1Data[1]){
servo1Data[1]++;
}else{
servo1Data[1]--;
}
servo1.write(servo1Data[1]);
}
returnPos = 1;//return 1 if still moving
}
return returnPos;
}
Example 2: millisServoV2.ino
Click to Download code: millisServoV2.ino
This sketch expands example 1 to 3 servos. Each is moving independently of the others, all at different speeds and directions.
/* millisServoV2
20/04/2024
This version is controlling 2 servo on independent timings
*/
#include
Servo servo1; // create servo object to control a servo
//This will store the data for servo1
unsigned int servo1Data[3];//moveTo, currentPos, speed
unsigned long servo1millis;
Servo servo2; // create servo object to control a servo
//This will store the data for servo1
unsigned int servo2Data[3];//moveTo, currentPos, speed
unsigned long servo2millis;
Servo servo3; // create servo object to control a servo
//This will store the data for servo1
unsigned int servo3Data[3];//moveTo, currentPos, speed
unsigned long servo3millis;
unsigned long currentMillis;//Holds the current board time in milliseconds
void setup() {
Serial.begin(9600);
Serial.println("millisServoV1");
servo1.attach(8); // attaches the servo on pin 8 to the servo object
servo2.attach(9); // attaches the servo on pin 9 to the servo object
servo3.attach(10); // attaches the servo on pin 10 to the servo object
}
void loop() {
int servoFinished;
currentMillis = millis();
servoFinished = servo1Control();//controls servo 1
if(servoFinished < 1){//If 0 is returned the servo has reached it's destination
servo1Data[0] = random(179); //pick a random angle between 0 - 179
servo1Data[2] = random(1,100); // pick a random speed between 1 and 100...speed in milliseconds per degree moved
Serial.print("Servo 1 Next Pos: ");
Serial.print(servo1Data[0]);
Serial.print(" Servo 1 Next Speed: ");
Serial.println(servo1Data[2]);
}
servoFinished = servo2Control();//controls servo 2
if(servoFinished < 1){//If 0 is returned the servo has reached it's destination
if(servo2Data[0] > 0){
servo2Data[0] = 0;
}else{
servo2Data[0] = 179;
}
servo2Data[2] = 30; // speed
Serial.print("Servo 2 Next Pos: ");
Serial.print(servo2Data[0]);
Serial.print(" Servo 2 Next Speed: ");
Serial.println(servo2Data[2]);
}
servoFinished = servo3Control();//controls servo 3
if(servoFinished < 1){//If 0 is returned the servo has reached it's destination
if(servo3Data[0] > 0){
servo3Data[0] = 0;
}else{
servo3Data[0] = 100;
}
servo3Data[2] = 10; // speed
Serial.print("Servo 3 Next Pos: ");
Serial.print(servo3Data[0]);
Serial.print(" Servo 3 Next Speed: ");
Serial.println(servo3Data[2]);
}
}
int servo1Control(){
int returnPos;
returnPos = 0;//return 0 if reached destination
if(servo1Data[0] > 179){
servo1Data[0] = 179;//limit check in case soeone tried to move servo more than 179 degrees
}
if(servo1Data[0] != servo1Data[1]){//is there still a distance to move
if(currentMillis - servo1millis >= servo1Data[2]){//is it time to move
servo1millis = currentMillis;
if(servo1Data[0] > servo1Data[1]){
servo1Data[1]++;
}else{
servo1Data[1]--;
}
servo1.write(servo1Data[1]);
}
returnPos = 1;//return 1 if still moving
}
return returnPos;
}
int servo2Control(){
int returnPos;
returnPos = 0;//return 0 if reached destination
if(servo2Data[0] > 179){
servo2Data[0] = 179;//limit check in case soeone tried to move servo more than 179 degrees
}
if(servo2Data[0] != servo2Data[1]){//is there still a distance to move
if(currentMillis - servo2millis >= servo2Data[2]){//is it time to move
servo2millis = currentMillis;
if(servo2Data[0] > servo2Data[1]){
servo2Data[1]++;
}else{
servo2Data[1]--;
}
servo2.write(servo2Data[1]);
}
returnPos = 1;//return 1 if still moving
}
return returnPos;
}
int servo3Control(){
int returnPos;
returnPos = 0;//return 0 if reached destination
if(servo3Data[0] > 179){
servo3Data[0] = 179;//limit check in case soeone tried to move servo more than 179 degrees
}
if(servo3Data[0] != servo3Data[1]){//is there still a distance to move
if(currentMillis - servo3millis >= servo2Data[2]){//is it time to move
servo3millis = currentMillis;
if(servo3Data[0] > servo3Data[1]){
servo3Data[1]++;
}else{
servo3Data[1]--;
}
servo3.write(servo3Data[1]);
}
returnPos = 1;//return 1 if still moving
}
return returnPos;
}
Additional Resource Links
Lesson 11: Arrays 28/08/2021
State Machine Examples 08/03/2023
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