Stepper question regarding potentiometer and map

Projects Programming
1

hi all. So i've built a arduino powered radial arm saw/grinder for cutting thick metal plate and it works perfectly going back and forth slowing cutting thru the metal. I'm in the process of adding a feed screw that will lower the saw a little after each pass, and had a quick question.

a snipit of code of it is this below.

int feedReading = analogRead(A1);
int feedStep = map(feedReading, 1, 1023, 0, 200);

This would give me movement of the stepper feedscrew from 0 steps to 200 steps on each pass. But regarding the map function, is it permissible to change it to: map(feedReading, 1, 1023, -200, 200) so i can have both forward and backward movement for the stepper while using the same Pot? so the middle range of the Pot would be 0, and the low range on the pot would go backwards, and the upper range of the pot moves it forward?

Is there any issue with doing it like this? It's going to be tonight before i'm able to upload the new code and actually try it out once i finish fabbing the stepper's feedscrew and get it mounted to the saw, so i figured i'd ask because i've never tried running negative numbers in the map function and didn't know if it would work like i think it would.

thanks

2

is it permissible to change it to: map(feedReading, 1, 1023, -200, 200)

Yes. But why 1 and not 0 for the first parameter?

Some code to test the map function:

void setup()
{
   Serial.begin(115200);
}

void loop()
{
   // set line endings in serial monitor to No line ending.
   // enter a int number in serial monitor and send
   if(Serial.available())
   {
   int input = Serial.parseInt();
   int output = map(input, 0, 1023, -200, 200);
   Serial.println(output);
   }
}
3

You can always read the documentation

4

in the beginning i had issues with my stepper motor seeming to lock everything up, and at the time i wanted the map to always have a voltage instead of 0, which would be ground, i would think. but it was actually the next parameter, the speed of the stepper had to be greater than 1. but it worked so i left it, but i've since cleaned it up and changed it to 0.

today i pretty much got everything working and usable. it could be better if i can learn how to do an interrupt in the code, so that'll be my test study item.

thanks