src/modules/tools/temperaturecontrol/TemperatureControl.cpp

   1 #include "mbed.h"
   2 #include "libs/Module.h"
   3 #include "libs/Kernel.h"
   4 #include <math.h>
   5 #include "TemperatureControl.h"
   6
   7 TemperatureControl::TemperatureControl(){
   8     this->error_count = 0;
   9 }
  10
  11 void TemperatureControl::on_module_loaded(){
  12
  13     // We start now desiring any temp
  14     this->desired_adc_value = UNDEFINED;
  15
  16     // Settings
  17     this->on_config_reload(this);
  18
  19     this->acceleration_factor = 10;
  20
  21     // Setup pins and timer
  22     this->thermistor_pin = new AnalogIn(p20);
  23     this->kernel->slow_ticker->attach( this, &TemperatureControl::thermistor_read_tick );
  24     this->heater_pwm = new PwmOut(p22);
  25     this->heater_pwm->write(0);
  26     this->pwm_value = 0;
  27
  28     // Register for events
  29     this->register_for_event(ON_GCODE_EXECUTE);
  30
  31 }
  32
  33
  34 // Get configuration from the config file
  35 void TemperatureControl::on_config_reload(void* argument){
  36
  37     this->readings_per_second = this->kernel->config->value(readings_per_second_ckeckusm     )->by_default(5     )->as_number();
  38
  39     // Values are here : http://reprap.org/wiki/Thermistor
  40     // TODO: WARNING : THIS WILL CHANGE and backward compatibility will be broken for config files that use this
  41     this->r0 =                  this->kernel->config->value(temperature_control_r0_ckeckusm  )->by_default(100000)->as_number();               // Stated resistance eg. 100K
  42     this->t0 =                  this->kernel->config->value(temperature_control_t0_ckeckusm  )->by_default(25    )->as_number() + 273.15;      // Temperature at stated resistance, eg. 25C
  43     this->beta =                this->kernel->config->value(temperature_control_beta_ckeckusm)->by_default(4066  )->as_number();               // Thermistor beta rating. See http://reprap.org/bin/view/Main/MeasuringThermistorBeta
  44     this->vadc =                this->kernel->config->value(temperature_control_vadc_ckeckusm)->by_default(3.3   )->as_number();               // ADC Reference
  45     this->vcc  =                this->kernel->config->value(temperature_control_vcc_ckeckusm )->by_default(3.3   )->as_number();               // Supply voltage to potential divider
  46     this->r1 =                  this->kernel->config->value(temperature_control_r1_ckeckusm  )->by_default(0     )->as_number();
  47     this->r2 =                  this->kernel->config->value(temperature_control_r2_ckeckusm  )->by_default(4700  )->as_number();
  48
  49     this->k = this->r0 * exp( -this->beta / this->t0 );
  50
  51     if( r1 > 0 ){
  52         this->vs = r1 * this->vcc / ( r1 + r2 );
  53         this->rs = r1 * r2 / ( r1 + r2 );
  54     }else{
  55         this->vs = this->vcc;
  56         this->rs = r2;
  57     }
  58
  59 }
  60
  61 void TemperatureControl::on_gcode_execute(void* argument){
  62     Gcode* gcode = static_cast<Gcode*>(argument);
  63
  64     // Set temperature
  65     if( gcode->has_letter('M') && gcode->get_value('M') == 104 && gcode->has_letter('S') ){
  66         this->set_desired_temperature(gcode->get_value('S'));
  67     }
  68
  69     // Get temperature
  70     if( gcode->has_letter('M') && gcode->get_value('M') == 105 ){
  71         this->kernel->serial->printf("get temperature: %f \r\n", this->get_temperature() );
  72     }
  73 }
  74
  75 void TemperatureControl::set_desired_temperature(double desired_temperature){
  76     this->desired_adc_value = this->temperature_to_adc_value(desired_temperature);
  77     this->tail_adc_value =  this->temperature_to_adc_value(desired_temperature-20);
  78     this->head_adc_value =  this->temperature_to_adc_value(desired_temperature+5);
  79 }
  80
  81 double TemperatureControl::get_temperature(){
  82     double temp = this->new_thermistor_reading() ;
  83     return this->adc_value_to_temperature( this->new_thermistor_reading() );
  84 }
  85
  86 double TemperatureControl::adc_value_to_temperature(double adc_value){
  87     double v = adc_value * this->vadc;            // Convert from 0-1 adc value to voltage
  88     double r = this->rs * v / ( this->vs - v );   // Resistance of thermistor
  89     return ( this->beta / log( r / this->k )) - 273.15;
  90 }
  91
  92 double TemperatureControl::temperature_to_adc_value(double temperature){
  93     double r = this->r0 * exp( this->beta * ( 1 / (temperature + 273.15) -1 / this->t0 ) ); // Resistance of the thermistor
  94     double v = this->vs * r / ( this->rs + r );                                             // Voltage at the potential divider
  95     return v / this->vadc * 1.00000;                                               // The ADC reading
  96 }
  97
  98 void TemperatureControl::thermistor_read_tick(){
  99
 100     double reading = this->new_thermistor_reading();
 101     if( this->desired_adc_value != UNDEFINED ){
 102         double difference = fabs( reading - this->desired_adc_value );
 103         double adjustment = difference / acceleration_factor / this->readings_per_second;
 104         if( reading > this->tail_adc_value ){
 105             this->heater_pwm->write( 1 );
 106         }else if( reading < this->head_adc_value ){
 107             this->pwm_value -= adjustment;
 108             this->heater_pwm->write( 0 );
 109         }else{
 110            if( reading > this->desired_adc_value ){
 111                 this->pwm_value += adjustment;  // Heat up
 112             }else{
 113                 this->pwm_value -= adjustment;  // Heat down
 114             }
 115             this->pwm_value = max( double(0), min( double(1), pwm_value ) );
 116             this->heater_pwm->write( pwm_value );
 117         }
 118     }
 119
 120 }
 121
 122 double TemperatureControl::new_thermistor_reading(){
 123     double new_reading = this->thermistor_pin->read();
 124
 125     if( this->queue.size() < 15 ){
 126         this->queue.push_back( new_reading );
 127         //this->kernel->serial->printf("first\r\n");
 128         return new_reading;
 129     }else{
 130         double current_temp = this->average_adc_reading();
 131         double error = fabs(new_reading - current_temp);
 132         if( error < 0.1 ){
 133             this->error_count = 0;
 134             double test;
 135             this->queue.pop_front(test);
 136             this->queue.push_back( new_reading );
 137         }else{
 138             this->error_count++;
 139             if( this->error_count > 4 ){
 140                 double test;
 141                 this->queue.pop_front(test);
 142             }
 143         }
 144         return current_temp;
 145     }
 146 }
 147
 148
 149 double TemperatureControl::average_adc_reading(){
 150     double total;
 151     int j=0;
 152     int reading_index = this->queue.head;
 153     while( reading_index != this->queue.tail ){
 154         j++;
 155         total += this->queue.buffer[reading_index];
 156         reading_index = this->queue.next_block_index( reading_index );
 157     }
 158     return total / j;
 159 }
 160
 161
 162