Arduino uno Bit overflow... need help solving this

[MikeJuszkie]

I am currently working on my own power supply that is controlled by an arduino. I am having issues with bit overflow, for current 5 volts is going to represent 1 Amp. The 5 volts in pwm is represented with a value of 255 but I would like to convert this value to 1000 mA. Everything I have tried has failed and I know the issue is that there is a loss of data when doing the math due to bit overflow. Can somebody please help.


here is the section of code that I am dealing with that I am having the problems with.

        int Vout = analogRead(pinVread);
        int Cout = analogRead(pinCread);
       
        float Vset = (voltage / 25.5);
        float Cset = current * (1000 / 255);
       
        float vout = (Vout / 102.3);
        float cout = Cout * (1000/ 1023);

The variables (voltage) and (current) are used much earlier in the program as the PWM outputs.


whenever it goes to display the value, instead of displaying a max of 1000 mA it shows a max of 765. and if you do the math, you will see that am losing everything after the decimal place for the "(1000/255)"

In the case of the second half those values are read from the analog inputs which are 10 bit not 8 bit. That one will not even show that value at all.

[MikeJuszkie]

I actually just fixed the issue. I just needed to add a  .00 to the end of the numbers I was using.

[MikeJuszkie]

 
        int Vout = analogRead(pinVread);
        int Cout = analogRead(pinCread);
       
        float Vset = (voltage / 25.5);
        float Cset = current * (1000.00 / 255.00);
       
        float vout = (Vout / 102.3);
        float cout = Cout * (1000.00/ 1023.00);
       

[Chet T16]

Is it not because you're using integer division? Changing it to 1000.0 will force it to using floating point?

Or am I not reading the question right?

[Chet T16]

Damn you tapatalk and your non notification of replies :p

[darrylp]

the MAP function will scale values from one range to another.

its documented on the arduino.cc web page.