File content as of revision 27:bb97231d1be9:

/*------------------------------------------------------------------------------
Library code file for interface to Heater
Date: 16/07/2018


------------------------------------------------------------------------------*/
#include "mbed.h"
#include "MODSERIAL.h"
#include "Heater.h"
#include "ADS8568_ADC.h"

extern Timer timer;
extern ADS8568_ADC adc;
extern DigitalIn adc_busy;
extern MODSERIAL pc;  
extern DigitalOut led_0;
extern FastPWM drive_1;
extern FastPWM drive_2;
extern FastPWM guard_1;
extern FastPWM guard_2;
    
Heater::Heater(const memspcr_ThermalConfiguration & thermal)
    :thermal(thermal)
    {
        if (thermal.selected_heater == memspcr_ThermalConfiguration_Heater_MAIN)
        {
            i_port = 0;
            v_port = 1;
            drive = & drive_1;
            guard = & guard_1;   
        }
        else if (thermal.selected_heater == memspcr_ThermalConfiguration_Heater_LYSIS)
        {
            i_port = 2;
            v_port = 3;
            drive = & drive_2;
            guard = & guard_2;
        }
        else pc.printf("Please select the desired heater channel");
        drive->prescaler(1);
        guard->prescaler(1);
        drive->period_ticks(1000);
        guard->period_ticks(1000);
    }
            


void Heater::log()const
{
    //Prints the current state to the terminal
    pc.printf("%d,%f,%f,%f,%f,%f\n",timer.read_ms(),R_ref,R,error,error_integrated,drive->read());
}

void Heater::read()
{
    //Reads R and then resets the drive back to its previous value
    int i = 0;    
    double drive_prev = drive->read();     //Store previous value of drive
    *drive = 1.0f;              //Turn the driver on for the measurement
    wait_us(thermal.adc_settling_time_us);        //Wait for ADC to settle
    adc.start_conversion(15);

    //Incremental back off until ADC is free
    while(adc_busy == 1)
        {
            wait_us(1);
            i++;
        }        

    drive->write(0);       //Reset the duty cycle back to what it was

    //Get voltage, current and R values from the ADC conversion
    adc.read_channels();
    curr = adc.read_channel_result(i_port);
    v = adc.read_channel_result(v_port);
    
    if (curr > 0) {R = (float)v/curr;}        //Avoid dividing by 0

    //Get error values
    
    error = R_ref - R;
    
    //Only allow positive integrated errors and limit change in integrated error
    //to help avoid integral windup    
    
    if (abs(error) < WIND_UP_LIMIT) {error_integrated += error;}
    if (error_integrated < 0.0) {error_integrated = 0.0;}
    pc.printf("%f\n",R);

}




void Heater::update()
{
    //Update PWM from setpoint and resistance
    drive->write((double) (thermal.adc_settling_time_us * (error + error_integrated/thermal.pid_integral_time)));
    guard->write((double) (thermal.adc_settling_time_us * thermal.guard_drive_ratio * (error + error_integrated/thermal.pid_integral_time)));

}



void Heater::Set_ref(float R) 
{
    R_ref = R;
}
void Heater::Set_D(float D) {
    drive->write(D);
    guard->write(D*thermal.guard_drive_ratio);
    }

int Heater::Get_i() const {return curr;}
int Heater::Get_v() const {return v;}

float Heater::Get_R() const {return R;}

void Heater::turn_on () 
{
    *drive = 1;
    *guard = thermal.guard_drive_ratio;
}

void Heater::turn_off () 
{
    *drive = 0;
    *guard = 0;
}