ESP32 Forum

Posted: **Fri May 01, 2020 6:50 pm**

Hello,
Kind of a noob but have been playing with ESP32s for a bit.
Doing a battery box project and will have 3 to 4 4 wire 12V PC fans for cooling.
I am trying to get an RPM reading on each individual fan.
I found a sketch that was meant for an Arduino UNO and it did exactly what I wanted it to do so I tried it on an ESP32s and no go.
I found out why and after getting the attachInterrupt right and it is working just fine on the ESP32 but for only 1 fan. I have tried to figure out how to get 2 or 3 more fans to give me a reading but am stuck. Basically at this point I don't know where to begin.
If anyone can point me in the right direction it would be greatly appreciated.
Here is the sketch.
Wolf

Code: Select all

//code by Crenn from http://thebestcasescenario.com
//project by Charles Gantt from http://themakersworkbench.com
//To disable interrupts: cli(); disable global interrupts and
//to enable them: sei(); enable interrupts

//Variables used for calculations
int NbTopsFan;
int Calc;

//The pin location of the sensor
int hallsensor = 33; typedef struct
{

  //Defines the structure for multiple fans and
  //their dividers
  char fantype;
  unsigned int fandiv;
} fanspec;

//Definitions of the fans
//This is the variable 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
//Variables used for calculations

void setup()
{
  Serial.begin(115200);
  pinMode(hallsensor, INPUT);
  attachInterrupt(digitalPinToInterrupt(hallsensor), rpm, FALLING);

  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 approximately the frequency 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");

  }

ESP32 Forum

RPM measurements on multiple 4 wire 12V fans

RPM measurements on multiple 4 wire 12V fans