Arduino Loop not recognizing break condition? - arduino

Question

I currently have a nested for loop system that is writing commands to a motor and reading from the attached encoder. For some reason, the program will not break out of the loop using the conditional. I have used some print statements to debug a little and it clearly recognizes that PWMcount is greater than 76 as it prints as far as I will let it count. Any advice is much appreciated, Thank You!
for(int PWMcount = 58;PWMcount < 76;) { //10-20 RAMP
for (int counter = 1; counter < 4;) {
if (counter != 3) {
finalTime = millis();
float newPos;
newPos = encoder.read();
if (newPos != oldPos) {
deltaTime = (finalTime - initialTime);
deltaPos = (newPos-oldPos);
oldPos = newPos;
initialTime = finalTime;
//Serial.println(deltaPos/deltaTime);
}
counter = counter+1;
delay(100);
// Serial.println(PWMcount);
}
else {
finalTime = millis(); //catches time for beginning of each loop iteration
float newPos;
newPos = encoder.read();
if (newPos != oldPos) { //Checks for encoder movement
deltaTime = (finalTime - initialTime); //calculates deltaT in milliseconds
deltaPos = (newPos-oldPos); //sets change in position from one iteration to the next
oldPos = newPos; //Sets old to new to fail if statement unless movement is detected.
initialTime = finalTime; //sets time at beginning of loop to time of ending last loop in order to correctly calculate deltaT in the next iteration
//Serial.println(deltaPos/deltaTime); //Prints rate of the encoder disk in deg/ms (Confirmed by manually taking data and seeing that 1 Rotation outputs values from 0-360
}
counter = 1;
PWMcount=PWMcount+1;
analogWrite(RPWM_Output, PWMcount); // Increases Motor PWM in accordance to loop
}
Serial.println(PWMcount); // UNCOMMENT TO TROUBLESHOOT PWM
delay(100);
}
}

Answer 1

This for loop never completes:
for (int counter = 1; counter < 4;)
The body of the loop is a single if statement. On the last iteration of the loop, the else branch is taken, and that branch sets the loop variable counter back to 1, so the expression counter < 4 is always true, and so that loop never exits.
Since it never exits, the code never gets to a point where the outer loop conditional is tested, nor where the outer loop would ever branch back to the beginning at all.
One possible way to fix the situation would be to combine the two loop conditions, making it a single loop:
for(int PWMcount = 58, counter = 1; PWMcount < 76;) { //10-20 RAMP
if (counter != 3) {
finalTime = millis();
float newPos;
newPos = encoder.read();
if (newPos != oldPos) {
deltaTime = (finalTime - initialTime);
deltaPos = (newPos-oldPos);
oldPos = newPos;
initialTime = finalTime;
//Serial.println(deltaPos/deltaTime);
}
counter = counter+1;
delay(100);
// Serial.println(PWMcount);
}
else {
finalTime = millis(); //catches time for beginning of each loop iteration
float newPos;
newPos = encoder.read();
if (newPos != oldPos) { //Checks for encoder movement
deltaTime = (finalTime - initialTime); //calculates deltaT in milliseconds
deltaPos = (newPos-oldPos); //sets change in position from one iteration to the next
oldPos = newPos; //Sets old to new to fail if statement unless movement is detected.
initialTime = finalTime; //sets time at beginning of loop to time of ending last loop in order to correctly calculate deltaT in the next iteration
//Serial.println(deltaPos/deltaTime); //Prints rate of the encoder disk in deg/ms (Confirmed by manually taking data and seeing that 1 Rotation outputs values from 0-360
}
counter = 1;
PWMcount=PWMcount+1;
analogWrite(RPWM_Output, PWMcount); // Increases Motor PWM in accordance to loop
Serial.println(PWMcount); // UNCOMMENT TO TROUBLESHOOT PWM
delay(100);
}
}
A couple of notes:
The loop condition does not bother to check the counter value, because the loop body obviates the comparison. The counter variable is always less than 4.
I moved the last two lines of the outer loop into the else branch of the if statement. They never executed in your original code, so maybe you just want to remove them altogether. But if the intent was to execute those two lines each line the inner loop reached its end (i.e. counter is 3), then this change matches that intent.