Help with a pc fan project.

Using Arduino Programming Questions
#1

Hi.

I have a Intel 4 pin fan ( FHP 6074; Black - GND; Yellow - 12V; Green - Tach; Blue - PWM) and I want to make the following project:

In Serial Monitor I want to give the fan the command to spin with X RPM (Ex: 1500 RPM). Next, on an LCD
I want to read the fan speed to see if it's the same with the one desired.

I tried a lot of codes but none worked as I wanted.

Someone can help me please?

#2

post your most promising code..

How do you measure the spin speed?

#3

I tried to combine these codes, but no succes. And also i tried to convert PWM to RPM .

speed.txt (1.35 KB)

control.txt (993 Bytes)

#4

can't read that on my smartphone.. see how to post code (using code tags) in the "how to use the forum" section

#5

This in the control file

word VentPin = 3;

void setup() {
  pinMode(VentPin, OUTPUT);
  pwm25kHzBegin();
}

void loop() {
  pwmDuty(19); // 25% (range = 0-79 = 1.25-100%)
  delay(5000);
  pwmDuty(39); // 50% (range = 0-79 = 1.25-100%)
  delay (5000);
  pwmDuty(59); // 75% (range = 0-79 = 1.25-100%)
  delay (5000);
}

void pwm25kHzBegin() {
  TCCR2A = 0;                               // TC2 Control Register A
  TCCR2B = 0;                               // TC2 Control Register B
  TIMSK2 = 0;                               // TC2 Interrupt Mask Register
  TIFR2 = 0;                                // TC2 Interrupt Flag Register
  TCCR2A |= (1 << COM2B1) | (1 << WGM21) | (1 << WGM20);  // OC2B cleared/set on match when up/down counting, fast PWM
  TCCR2B |= (1 << WGM22) | (1 << CS21);     // prescaler 8
  OCR2A = 79;                               // TOP overflow value (Hz)
  OCR2B = 0;
}

void pwmDuty(byte ocrb) {
  OCR2B = ocrb;                             // PWM Width (duty)
}

This is the speed file

//project done by www.theorycircuit.com
//code by Crenn from http://thebestcasescenario.com  thank you!
//Varibles used for calculations
int NbTopsFan; int Calc;
 
//The pin location of the sensor
int hallsensor = 2; typedef struct{
 
//Defines the structure for multiple fans and 
//their dividers 
char fantype;
unsigned int fandiv; }fanspec;
 
//Definitions of the fans
//This is the varible used to select the fan and it's divider,
//set 1 for unipole hall effect sensor
//and 2 for bipole hall effect sensor
fanspec fanspace[3]={{0,1},{1,2},{2,8}}; char fan = 1;
 
void rpm ()
//This is the function that the interupt calls
{ NbTopsFan++; }
 
//This is the setup function where the serial port is initialised,
//and the interrupt is attached
void setup()
{ pinMode(hallsensor, INPUT);
Serial.begin(9600);
attachInterrupt(0, rpm, RISING); }
 
void loop ()
//Set NbTops to 0 ready for calculations
{ NbTopsFan = 0;
 
//Enables interrupts
sei();
 
//Wait 1 second
delay (1000);
 
//Disable interrupts
cli();
 
//Times NbTopsFan (which is apprioxiamately the fequency the fan 
//is spinning at) by 60 seconds before dividing by the fan's divider
Calc = ((NbTopsFan * 60)/fanspace[fan].fandiv);
 
//Prints the number calculated above
Serial.print (Calc, DEC);
 
//Prints " rpm" and a new line
Serial.print (" rpm\r\n");
}
#6

do you have a Hall sensor on your fan?

do you get what this line does fanspec fanspace[3]={{0,1},{1,2},{2,8}};

#7

I think a better approach would be to power up your motor and get variable speed working , write your own code to do that . Then get the lcd working , then try and measure the rpm using that third wire .
Finding a couple of bits of code , then sticking them together is not the way in my opinion .

#8