RPM control using PWM for blower ba5025h12b

Projects Programming
22

for 100% pwm 40,000 RPM is what is expected as per datasheet im getting a sudden spike in between 34K in the above observation but again it starts to vary

23

is it because of arduino uno? due to noise and all? i've read it can prove to be inaccurate at times?
should i change arduino uno and use something else? But it is possible to get it with uno right?

24

Try this version with millis timer instead of delay():

const int pwm_pin = 9;
const int tach_pin = 2;
volatile unsigned long pulse_count = 0;
unsigned long pulseCopy,
              timerStart,
              elapsed;
unsigned int rpm, timerEnd = 1000;
const int pulses_per_revolution = 2;
int pwm = 255;  

void setup() {
  Serial.begin(9600);
  pinMode(pwm_pin, OUTPUT);
  analogWrite(pwm_pin, 0);
  pinMode(tach_pin, INPUT);
  attachInterrupt(digitalPinToInterrupt(tach_pin), pulseCounter, FALLING);
  analogWrite(pwm_pin, pwm);
}

void loop() {
  elapsed = millis() - timerStart;
  if(elapsed >= timerEnd)
  {
    timerStart += timerEnd;  
    noInterrupts();
    pulseCopy = pulse_count;
    pulse_count = 0;
    interrupts();
    rpm = (pulseCopy * 60) / pulses_per_revolution;

    Serial.print("PWM is: ");
    Serial.print(map(pwm, 0, 255, 0, 100));
    Serial.print("%, RPM: ");
    Serial.print(rpm);
    Serial.println(" rpm");
  }  
}

void pulseCounter() {
  pulse_count++;
}
25

i tried that and with that i get this:

image
image286×520 3.49 KB

its shown 40k in datasheet so with its tolerance it could be in this range right?
so is it working fine?

26 
const int pwm_pin = 9;       
const int tach_pin = 2;      
volatile unsigned long pulse_count = 0;
unsigned long pulseCopy, timerStart, elapsed;
unsigned int rpm, timerEnd = 1000;
const int pulses_per_revolution = 2;
int pwm = 0;                

void setup() {
  Serial.begin(9600);
  pinMode(pwm_pin, OUTPUT);
  analogWrite(pwm_pin, pwm);
  pinMode(tach_pin, INPUT);
  attachInterrupt(digitalPinToInterrupt(tach_pin), pulseCounter, FALLING);
}

void loop() {
  elapsed = millis() - timerStart;
  if (elapsed >= timerEnd) {
    timerStart += timerEnd;  
    noInterrupts();
    pulseCopy = pulse_count;
    pulse_count = 0;
    interrupts();
    rpm = (pulseCopy * 60) / pulses_per_revolution;

    Serial.print("PWM is: ");
    Serial.print(map(pwm, 0, 255, 0, 100));
    Serial.print("%, RPM: ");
    Serial.print(rpm);
    Serial.println(" rpm");

    pwm += 51;
    if (pwm > 255) {
      pwm = 0; 
    }
    analogWrite(pwm_pin, pwm);
  }
}

void pulseCounter() {
  pulse_count++;
}

i modified your code to find values from duty cycle of 0 to 100% in increments of 20% and its varying a lot from the datasheet
PWM is: 0%, RPM: 14820 rpm

PWM is: 20%, RPM: 21870 rpm

PWM is: 40%, RPM: 21540 rpm

PWM is: 60%, RPM: 21210 rpm

PWM is: 80%, RPM: 28680 rpm

PWM is: 100%, RPM: 11550 rpm

PWM is: 0%, RPM: 14760 rpm

PWM is: 20%, RPM: 20730 rpm

PWM is: 40%, RPM: 20700 rpm

PWM is: 60%, RPM: 25110 rpm

PWM is: 80%, RPM: 40770 rpm

PWM is: 100%, RPM: 22380 rpm

PWM is: 0%, RPM: 14820 rpm

PWM is: 20%, RPM: 38684 rpm

PWM is: 40%, RPM: 44098 rpm

PWM is: 60%, RPM: 31754 rpm

PWM is: 80%, RPM: 0 rpm

PWM is: 100%, RPM: 0 rpm

PWM is: 0%, RPM: 120 rpm

PWM is: 20%, RPM: 3990 rpm

PWM is: 40%, RPM: 54104 rpm

PWM is: 60%, RPM: 21690 rpm

PWM is: 80%, RPM: 28050 rpm

PWM is: 100%, RPM: 45000 rpm

PWM is: 0%, RPM: 15150 rpm

PWM is: 20%, RPM: 24390 rpm

PWM is: 40%, RPM: 25890 rpm

PWM is: 60%, RPM: 30060 rpm

PWM is: 80%, RPM: 34770 rpm

PWM is: 100%, RPM: 28500 rpm

datasheet expected values :

image

27

Well, appears better what do you see with PWM 240, 192, 160?

28

What does the chopped off top line of that picture say?

29

columns heading are serial number,percentage,rotating speed and unit from the left most column

30

OK, what speed if PWM wire is disconnected, zero or full speed?

31

full speed

32

at 240 its varying too much again

image
image292×573 4.37 KB

33

That makes no sense, post your modified code.

34 

const int pwm_pin = 9;
const int tach_pin = 2;
volatile unsigned long pulse_count = 0;
unsigned long pulseCopy,
              timerStart,
              elapsed;
unsigned int rpm, timerEnd = 1000;
const int pulses_per_revolution = 2;
int pwm = 240;  

void setup() {
  Serial.begin(9600);
  pinMode(pwm_pin, OUTPUT);
  analogWrite(pwm_pin, 0);
  pinMode(tach_pin, INPUT);
  attachInterrupt(digitalPinToInterrupt(tach_pin), pulseCounter, FALLING);
  analogWrite(pwm_pin, pwm);
}

void loop() {
  elapsed = millis() - timerStart;
  if(elapsed >= timerEnd)
  {
    timerStart += timerEnd;  
    noInterrupts();
    pulseCopy = pulse_count;
    pulse_count = 0;
    interrupts();
    rpm = (pulseCopy * 60) / pulses_per_revolution;

    Serial.print("PWM is: ");
    Serial.print(map(pwm, 0, 255, 0, 100));
    Serial.print("%, RPM: ");
    Serial.print(rpm);
    Serial.println(" rpm");
  }  
}

void pulseCounter() {
  pulse_count++;
}
35

What is the output?

36

image
image946×611 6.41 KB

37

image
in datasheet

38

What RPM reading with PWM disconnected?

39 
const int tach_pin = 2;
volatile unsigned long pulse_count = 0;
unsigned long pulseCopy, timerStart, elapsed;
unsigned int rpm, timerEnd = 1000;
const int pulses_per_revolution = 2;

void setup() {
  Serial.begin(9600);
  pinMode(tach_pin, INPUT);
  attachInterrupt(digitalPinToInterrupt(tach_pin), pulseCounter, FALLING);
}

void loop() {
  elapsed = millis() - timerStart;
  if (elapsed >= timerEnd) {
    timerStart += timerEnd;
    noInterrupts();
    pulseCopy = pulse_count;
    pulse_count = 0;
    interrupts();
    rpm = (pulseCopy * 60) / pulses_per_revolution;

    Serial.print("RPM: ");
    Serial.print(rpm);
    Serial.println(" rpm");
  }
}

void pulseCounter() {
  pulse_count++;
}

i used the above code to measure rpm without pwm

output is:
image

40

ig its not full speed and is low when pwm pin is disconnected my bad

41

yet according to datasheet at 2% duty cycle its 2500rpm so like I'm confused
and when i set it to 2% its considerably higher