ESP32_Fan_Meter

#include <TFT_eSPI.h> // Graphics and font library for ILI9341 driver chip
#include <SPI.h>

//#define TFT_GREY 0x5AEB // New colour

// Pin Assignments
uint8_t Fan1_Pin 2;
uint8_t Fan2_Pin 15;
#define FAN1_PIN 2
#define FAN2_PIN 15

// unipole hall effect sensor, Div is 2
// bipole hall effect sensor, Div is 8
// Declare Fan struct
typedef struct{
    uint32_t Ticks;
    uint32_t RPM;
    uint8_t Div;
} Fan;

// Variables
Fan Fans[2];
uint8_t str_Fan1[16], str_Fan2[16];
TFT_eSPI tft = TFT_eSPI();  // Invoke library

// Interrupt Service Routines
void Fan1_Add_Ticks () { Fans[0].Ticks++; }
void Fan2_Add_Ticks () { Fans[1].Ticks++; }

// function to clear fan calculations
void clear_fans (){
    Fans[0].Ticks = 0;
    Fans[0].RPM = 0;
    Fans[1].Ticks = 0;
    Fans[1].RPM = 0;
}

void setup(){
    // Initalize GPIO pins
    pinMode(Fan1_Pin, INPUT);
    pinMode(Fan2_Pin, INPUT);

    // Initalize Serial port
    Serial.begin(9600);

    // Initalize TFT
    tft.init();
    tft.setRotation(2);

    // Initalize interrupt service
    attachInterrupt(digitalPinToInterrupt(Fan1_Pin), Fan1_Add_Ticks, RISING);
    attachInterrupt(digitalPinToInterrupt(Fan2_Pin), Fan2_Add_Ticks, RISING);

    // Set Fans Div
    Fans[0].Div = 2;
    Fans[1].Div = 2;
}

void loop (){
    //Set Fans Ticks to 0, ready for new calculations
    clear_fans;

    //Enables interrupts
    sei();

    //Wait 1 second
    delay (1000);

    //Disable interrupts
    cli();

    // Calculate the RPM of the Fans, RPM = (Ticks * 60) / Div
    Fans[0].RPM = ((Fans[0].Ticks * 60)/Fans[0].Div);
    Fans[1].RPM = ((Fans[1].Ticks * 60)/Fans[1].Div);

    // Output the RPM of the fans to the serial port.
    //str_Fan1 = "Fan1 RPM: " + Fans[0].RPM
    //str_Fan2 = "Fan2 RPM: " + Fans[1].RPM
    // https://cpp4arduino.com/2020/02/07/how-to-format-strings-without-the-string-class.html
    snprintf_P(str_Fan1, sizeof(str_Fan1), PSTR("Fan1 RPM: %u"), Fan[0].RPM);
    snprintf_P(str_Fan2, sizeof(str_Fan2), PSTR("Fan2 RPM: %u"), Fan[1].RPM);

    Serial.println (str_Fan1);
    Serial.println (str_Fan2);

    //Serial.print ("Fan1 RPM: ");
    //Serial.println (Fans[0].RPM, DEC);
    //Serial.print ("Fan2 RPM: ");
    //Serial.println (Fans[1].RPM, DEC);

    // Set "cursor" at top left corner of display (0,0) and select font 2
    // (cursor will move to next line automatically during printing with 'tft.println'
    //  or stay on the line is there is room for the text with tft.print)
    tft.setCursor(0, 0, 2);

    // Set the font colour to be green with black background, set to font 4
    tft.setTextColor(TFT_GREEN,TFT_BLACK);
    //tft.setTextFont(2);
    tft.println("Fan Meter");
    tft.println(str_Fan1);
    tft.println(str_Fan2);

}