Trouble Shooting with Timer1 code

Projects Programming
1

I want to take a 0.5-4.5V input and turn it into a 1-750hz square wave on a Arduino Atmega 328(There is also code in there that is setting outPin2 low unless there is 2.5V or more but that's not really what I'm concentrated on right now, in theory it should work fine). I don't know why it's not working, I vary the voltage in but it has little to no effect on the very inconsistent square wave (It is flipping out on the oscilloscope, it looks square like but it looks like it is vibrating rapidly on the screen and ranges from a frequency of 62hz to 129hz). Here is my code:

// constants won't change. Used here to set pin numbers:
#include <TimerOne.h>
#define pwmRegister OCR1A      // the logical pin, can be set to OCR1B

const int outPin = 9;      // the number of the digital pin used to output the frequency 
const int inPin = A0;    // the number of the analog pin recieving the voltage for the frequecy calculations

const int outPin2 = 3;     // the number of the digital pin used to 
const int inPin2 = A1;   // the number of the analog pin recieving the signal for the ignition switch

int sensorValue = 1;
int sensorValue2 = 1;

long period = 1;
long frequency = 1;

//int prescale[] = {0,1,8,64,256,1024};

void setup() 
{
  Serial.begin(9600);
  
  // set the digital pins as outputs:
  pinMode(outPin, OUTPUT);
  pinMode(outPin2, OUTPUT);
  
  Timer1.initialize(period);
}


void loop()
{
  // read the voltage going into pin A0
  sensorValue = analogRead(inPin); 
  
  // map it to the range of the analog out (0.5V to 4.5V represented by their bit equivalents is being converted into 1-750hz) :
  frequency = map(sensorValue, 102.4, 921.6, 1, 750);  
  
  Timer1.setPeriod(1 / frequency);
  
  Timer1.pwm(outPin, 512, period); 
  
  //read the voltage going into pin A1
  sensorValue = analogRead(inPin2);
  
  //Sets the output of digitalOut2 low
  digitalWrite(outPin2, LOW);
  
   //If there is there is 2.5V or more going into analogInPin2 digitalOut2 will go high 
  if (sensorValue2 > 512)
  {
    digitalWrite(outPin2, HIGH);
  }
}

Any ideas about what's going wrong or ways to figure it out?

2

bhay:
I want to take a 0.5-4.5V input and turn it into a 1-750hz square wave

You're trying to have the input voltage determine the output frequency?

3

I want the code to read the voltage in (which will be between 0.5V and 4.5V) and then map that to values of 1hz to 750hz. As the voltage varies so should the frequency.

4

The period is set in microseconds, not seconds. You are missing a factor of a million.

I suggest you check the frequency you have calculated. Since map() takes integer arguments and returns an integer, the float values you're supplying would be reduced to ints before the map() was performed, so you will need to check whether the results are as accurate as you want. I suggest you also calculate the period explicitly as an unsigned long value so you can check you end up with the correct value, and so that you can ensure none of the intermediate results are calculated as ints.

5

Thanks for the help guys, turns out my code was fine I just goofed with the wiring. Make sure you always ground your circuit from the same source you got your power (aka don't ground an oscilloscope using the Arduino and power it using a DC Power Supply because they have different references points or something like that).