SpeederControl

#include "SPI.h" // necessary library
int ss=10; // using digital pin 10 for SPI slave select
int del=10; // used for various delays
int button = 1;
float input_voltage = 0.0;
float temp=0.0;
float r1=90900.0;
float r2=10000.0;
int timer;
int limit;
int value;

void setup()
{
  Serial.begin(9600);     //  opens serial port, sets data rate to 9600 bps
  pinMode(ss, OUTPUT); // we use this for SS pin
  SPI.begin(); // wake up the SPI bus.
  SPI.setBitOrder(MSBFIRST);
  // our MCP4162 requires data to be sent MSB (most significant byte) first
  pinMode(button, INPUT);
  pinMode(A0, INPUT);
  digitalWrite(A0, LOW);
  timer = 0;
}

void setValue(int value)
{
  digitalWrite(ss, LOW);
  SPI.transfer(0); // send command byte
  SPI.transfer(value); // send value (0~255)
  digitalWrite(ss, HIGH);
}

void loop()
{

//Conversion formula

   int analog_value = analogRead(A0);
    temp = (analog_value * 5.0) / 1024.0;
   input_voltage = temp / (r2/(r1+r2)) * 10;

   if (input_voltage < 0.1)
   {
     input_voltage=0.0;
   }
    Serial.print("vt= ");
    Serial.println(input_voltage);
    /*
    Serial.print("t= ");
    Serial.println(timer);
    Serial.print("l= ");
    Serial.println(limit);
    Serial.print("va= ");
    Serial.println(value);*/

   timer += 1;
   delay(500);
   limit = 1250/(2*timer);

  if(input_voltage < 300){
    //timer = 0;
    //setValue(limit);
    }

}