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#include "pid.h"
#if MOTHERBOARD != 2
// Based on the excellent Wikipedia PID control article.
// See http://en.wikipedia.org/wiki/PID_controller
PIDcontrol::PIDcontrol(byte hp, byte tp, bool b)
{
heat_pin = hp;
temp_pin = tp;
doingBed = b;
if(doingBed)
{
pGain = B_TEMP_PID_PGAIN;
iGain = B_TEMP_PID_IGAIN;
dGain = B_TEMP_PID_DGAIN;
} else
{
pGain = E_TEMP_PID_PGAIN;
iGain = E_TEMP_PID_IGAIN;
dGain = E_TEMP_PID_DGAIN;
}
currentTemperature = 0;
setTarget(0);
pinMode(heat_pin, OUTPUT);
pinMode(temp_pin, INPUT);
}
/*
Set the target temperature. This also
resets the PID to, for example, remove accumulated integral error from
a long period when the heater was off and the requested temperature was 0 (which it
won't go down to, even with the heater off, so the integral error grows).
*/
void PIDcontrol::setTarget(int t)
{
targetTemperature = t;
previousTime = millis();
previousError = 0;
integral = 0;
}
/*
Temperature reading function
With thanks to: Ryan Mclaughlin - http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1230859336
for the MAX6675 code
*/
void PIDcontrol::internalTemperature(short table[][2])
{
#ifdef USE_THERMISTOR
int raw = 0;
for(int i = 0; i < 3; i++)
raw += analogRead(temp_pin);
raw = raw/3;
byte i;
// TODO: This should do a binary chop
for (i=1; i<NUMTEMPS; i++)
{
if (table[i][0] > raw)
{
currentTemperature = table[i-1][1] +
(raw - table[i-1][0]) *
(table[i][1] - table[i-1][1]) /
(table[i][0] - table[i-1][0]);
break;
}
}
// Overflow: Set to last value in the table
if (i >= NUMTEMPS) currentTemperature = table[i-1][1];
// Clamp to byte
//if (celsius > 255) celsius = 255;
//else if (celsius < 0) celsius = 0;
#endif
#ifdef AD595_THERMOCOUPLE
currentTemperature = ( 5.0 * analogRead(pin* 100.0) / 1024.0; //(int)(((long)500*(long)analogRead(TEMP_PIN))/(long)1024);
#endif
#ifdef MAX6675_THERMOCOUPLE
int value = 0;
byte error_tc;
digitalWrite(TC_0, 0); // Enable device
/* Cycle the clock for dummy bit 15 */
digitalWrite(SCK,1);
digitalWrite(SCK,0);
/* Read bits 14-3 from MAX6675 for the Temp
Loop for each bit reading the value
*/
for (int i=11; i>=0; i--)
{
digitalWrite(SCK,1); // Set Clock to HIGH
value += digitalRead(SO) << i; // Read data and add it to our variable
digitalWrite(SCK,0); // Set Clock to LOW
}
/* Read the TC Input inp to check for TC Errors */
digitalWrite(SCK,1); // Set Clock to HIGH
error_tc = digitalRead(SO); // Read data
digitalWrite(SCK,0); // Set Clock to LOW
digitalWrite(TC_0, 1); //Disable Device
if(error_tc)
currentTemperature = 2000;
else
currentTemperature = value/4;
#endif
}
void PIDcontrol::pidCalculation()
{
if(doingBed)
internalTemperature(bedtemptable);
else
internalTemperature(temptable);
time = millis();
float dt = 0.001*(float)(time - previousTime);
previousTime = time;
if (dt <= 0) // Don't do it when millis() has rolled over
return;
float error = (float)(targetTemperature - currentTemperature);
integral += error*dt;
float derivative = (error - previousError)/dt;
previousError = error;
int output = (int)(error*pGain + integral*iGain + derivative*dGain);
if(!doingBed && cdda[tail]->extruding())
output += EXTRUDING_INCREASE;
output = constrain(output, 0, 255);
analogWrite(heat_pin, output);
}
#endif
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