Problems with calibration.

Using Arduino Programming Questions
1

I'm trying to calibrate the LSM303 tilt-compensated compass with a button, and then use the calibrated values to grab the compass heading.
Now the problem is, when I add the line of code, which essentially grabs the heading, everything just messes up.

With this it does not calibrate, nor give a heading ( all is 0)

#include <Wire.h>
#include <LSM303.h>

int egoal;
int ogoal;
LSM303 compass;
const int buttonPin = 33; 
const int ledPin = 31;
int buttonState;

LSM303::vector running_min = {2047, 2047, 2047}, running_max = {-2048, -2048, -2048};

void setup() {
        Serial.begin(9600);
        pinMode(19, INPUT);
        pinMode(buttonPin, OUTPUT);
        pinMode(ledPin, OUTPUT);
        Wire.begin();
        compass.init();
        compass.enableDefault();
        attachInterrupt(4, calibrateCompass, LOW); //when button has been pushed,
}


void work() {
compass.read(); 
int headingz = compass.heading((LSM303::vector){0,-1,0});  
Serial.println(headingz);
}

void calibrateCompass() {
  compass.m_min.x = (running_min.x = min(running_min.x, compass.m.x));
  compass.m_min.y = (running_min.y = min(running_min.y, compass.m.y));
  compass.m_min.z = (running_min.z = min(running_min.z, compass.m.z));

  compass.m_max.x = (running_max.x = max(running_max.x, compass.m.x));
  compass.m_max.y = (running_max.y = max(running_max.y, compass.m.y));
  compass.m_max.z = (running_max.z = max(running_max.z, compass.m.z));
  digitalWrite(ledPin, HIGH);
}

void loop() {
  digitalWrite(buttonPin, HIGH);  
  buttonState = digitalRead(19);
  
  digitalWrite(ledPin, LOW);
  work();
  Serial.println(compass.m_min.x);// This is just to see if the values have been calibrated after using the pushbutton
  Serial.println(compass.m_min.y);
  Serial.println(compass.m_min.z);
  Serial.println("----------------------------");
  //
  
  delay(250);
}

with this, (note commented lines in void work):

#include <Wire.h>
#include <LSM303.h>

int egoal;
int ogoal;
LSM303 compass;
const int buttonPin = 33; 
const int ledPin = 31;
int buttonState;

LSM303::vector running_min = {2047, 2047, 2047}, running_max = {-2048, -2048, -2048};

void setup() {
        Serial.begin(9600);
        pinMode(19, INPUT);
        pinMode(buttonPin, OUTPUT);
        pinMode(ledPin, OUTPUT);
        Wire.begin();
        compass.init();
        compass.enableDefault();
        attachInterrupt(4, calibrateCompass, LOW); //when button has been pushed,
}


void work() {
compass.read(); 
//int headingz = compass.heading((LSM303::vector){0,-1,0});  
//Serial.println(headingz);
}

void calibrateCompass() {
  compass.m_min.x = (running_min.x = min(running_min.x, compass.m.x));
  compass.m_min.y = (running_min.y = min(running_min.y, compass.m.y));
  compass.m_min.z = (running_min.z = min(running_min.z, compass.m.z));

  compass.m_max.x = (running_max.x = max(running_max.x, compass.m.x));
  compass.m_max.y = (running_max.y = max(running_max.y, compass.m.y));
  compass.m_max.z = (running_max.z = max(running_max.z, compass.m.z));
  digitalWrite(ledPin, HIGH);
}

void loop() {
  digitalWrite(buttonPin, HIGH);  
  buttonState = digitalRead(19);
  
  digitalWrite(ledPin, LOW);
  work();
  Serial.println(compass.m_min.x);// This is just to see if the values have been calibrated after using the pushbutton
  Serial.println(compass.m_min.y);
  Serial.println(compass.m_min.z);
  Serial.println("----------------------------");
  //
  
  delay(250);



}

IT gives the calibrated values but not the heading. And on the pololu specifications it says the compass can be calibrated on the go or at the execution of a function.

What's wrong??? =( =( =( =( =( =( =(

2

Why do you think you need an interrupt to detect the switch press? Why is the interrupt called over and over while the switch is LOW? Typically, you want the interrupt called ONCE when the pin becomes LOW.

Why are some pin numbers assigned names and some not?

  digitalWrite(buttonPin, HIGH);

This appears to be trying to set the state of an input pin. Why would you be doing that? More importantly, why is an output pin called buttonPin? Switches are NOT output devices.

3

PaulS:
This appears to be trying to set the state of an input pin. Why would you be doing that? More importantly, why is an output pin called buttonPin? Switches are NOT output devices.

Internal pullup resistor perhaps?