The Technology Partnership / Heater_V2

Heater for threaded program

Dependents:   LEX_Threaded_Programming_V3

Heater.cpp@45:5f588512529b, 2019-11-16 (annotated)

Committer:
justinbuckland
Date:
Sat Nov 16 06:05:55 2019 +0000
Revision:
45:5f588512529b
Parent:
44:e358867319f6
Child:
46:47c394467c66
Added calculation of variance of resistance measurements

Who changed what in which revision?

UserRevisionLine numberNew contents of line
omatthews 0:4e33cc8171f4 1 /*------------------------------------------------------------------------------
omatthews 0:4e33cc8171f4 2 Library code file for interface to Heater
omatthews 0:4e33cc8171f4 3 Date: 16/07/2018
omatthews 0:4e33cc8171f4 4
omatthews 0:4e33cc8171f4 5
omatthews 0:4e33cc8171f4 6 ------------------------------------------------------------------------------*/
omatthews 1:4435d407d827 7 #include "mbed.h"
omatthews 1:4435d407d827 8 #include "MODSERIAL.h"
omatthews 0:4e33cc8171f4 9 #include "Heater.h"
omatthews 0:4e33cc8171f4 10 #include "ADS8568_ADC.h"
omatthews 0:4e33cc8171f4 11
justinbuckland 35:5acf01897ed6 12 Heater::Heater(const int i_port, const int v_port, const float cal_a, const float cal_b, FastPWM * drive, FastPWM * guard, ADS8568_ADC * adc, DigitalIn adc_busy, const memspcr_ThermalConfiguration & thermal)
justinbuckland 35:5acf01897ed6 13 :thermal(thermal), i_port(i_port), v_port(v_port), cal_a(cal_a), cal_b(cal_b), drive(drive), guard(guard), adc(adc), adc_busy(adc_busy)
omatthews 30:055d856f05b5 14 {
justinbuckland 42:166d9bc7675e 15 //Set up PWM
omatthews 30:055d856f05b5 16 drive->prescaler(1);
omatthews 30:055d856f05b5 17 guard->prescaler(1);
omatthews 30:055d856f05b5 18 drive->period_ticks(1000);
omatthews 30:055d856f05b5 19 guard->period_ticks(1000);
justinbuckland 42:166d9bc7675e 20
justinbuckland 42:166d9bc7675e 21 //Initialise values for averaging resistance
justinbuckland 42:166d9bc7675e 22 n_acc = 0;
justinbuckland 42:166d9bc7675e 23 R_acc = 0;
justinbuckland 45:5f588512529b 24 R2_acc = 0;
omatthews 30:055d856f05b5 25 }
omatthews 30:055d856f05b5 26
omatthews 2:7f15386fcc90 27 void Heater::read()
omatthews 0:4e33cc8171f4 28 {
omatthews 1:4435d407d827 29 //Reads R and then resets the drive back to its previous value
omatthews 30:055d856f05b5 30 int i = 0;
omatthews 17:0bfed0e96927 31 double drive_prev = drive->read(); //Store previous value of drive
justinbuckland 35:5acf01897ed6 32
justinbuckland 44:e358867319f6 33 *drive = 1.0f; //Turn the driver on for the measurement
justinbuckland 44:e358867319f6 34 wait_us(thermal.settling_time_us); //Wait for ADC to settle
justinbuckland 34:294adcc3e4b2 35 adc->start_conversion(ADC_CONV_ALL_CH);
justinbuckland 34:294adcc3e4b2 36
omatthews 18:f5d26d3d532f 37 //Incremental back off until ADC is free
omatthews 30:055d856f05b5 38 while(adc_busy == 1) {
omatthews 30:055d856f05b5 39 wait_us(1);
omatthews 30:055d856f05b5 40 i++;
omatthews 30:055d856f05b5 41 }
omatthews 25:09a315a59956 42
justinbuckland 44:e358867319f6 43 drive->write(0); //Reset the duty cycle back to what it was
omatthews 18:f5d26d3d532f 44
omatthews 18:f5d26d3d532f 45 //Get voltage, current and R values from the ADC conversion
omatthews 31:7c6f05326c4d 46 adc->read_channels();
omatthews 31:7c6f05326c4d 47 curr = adc->read_channel_result(i_port);
omatthews 31:7c6f05326c4d 48 v = adc->read_channel_result(v_port);
omatthews 30:055d856f05b5 49
justinbuckland 35:5acf01897ed6 50 if (curr > 0) { //Avoid dividing by 0
justinbuckland 35:5acf01897ed6 51 R = (float)v/curr;
justinbuckland 35:5acf01897ed6 52 R = cal_a + cal_b*R; //Convert to Ohms
omatthews 30:055d856f05b5 53 }
justinbuckland 42:166d9bc7675e 54
justinbuckland 45:5f588512529b 55 // Calculate accumulated resistance values for R_avg and R_var output
justinbuckland 42:166d9bc7675e 56 R_acc = R_acc + R;
justinbuckland 45:5f588512529b 57 R2_acc = R2_acc + R*R
justinbuckland 42:166d9bc7675e 58 n_acc ++;
justinbuckland 35:5acf01897ed6 59
omatthews 0:4e33cc8171f4 60 }
omatthews 0:4e33cc8171f4 61
omatthews 25:09a315a59956 62 void Heater::update()
omatthews 7:59ece353eea2 63 {
justinbuckland 44:e358867319f6 64
justinbuckland 41:b1602c68abcd 65 //Get error
justinbuckland 41:b1602c68abcd 66 error = R_ref - R;
justinbuckland 41:b1602c68abcd 67
omatthews 25:09a315a59956 68 //Update PWM from setpoint and resistance
paullj 39:5dffedda7a0d 69 double duty_cycle = thermal.pid_kp_mho * error;
justinbuckland 41:b1602c68abcd 70
justinbuckland 41:b1602c68abcd 71 //Get integrated error
paullj 39:5dffedda7a0d 72 if (thermal.pid_integral_time_ms > 0) // set integral time to zero to have no integral term
justinbuckland 41:b1602c68abcd 73 if (abs(error) > thermal.pid_wind_up_limit_ohm) error = error * thermal.pid_wind_up_limit_ohm / abs(error);
justinbuckland 41:b1602c68abcd 74 error_integrated += error * (float) thermal.thermal_control_loop_interval_ms;
paullj 39:5dffedda7a0d 75 duty_cycle += thermal.pid_kp_mho * error_integrated/thermal.pid_integral_time_ms;
justinbuckland 44:e358867319f6 76
paullj 39:5dffedda7a0d 77 if (duty_cycle > thermal.pid_pwm_limit)
paullj 39:5dffedda7a0d 78 duty_cycle = thermal.pid_pwm_limit;
paullj 39:5dffedda7a0d 79 else if (duty_cycle < 0)
paullj 39:5dffedda7a0d 80 duty_cycle = 0;
justinbuckland 36:a8130bd29349 81
omatthews 31:7c6f05326c4d 82 drive->write(duty_cycle);
justinbuckland 44:e358867319f6 83 guard->write(duty_cycle * thermal.guard_drive_ratio);
omatthews 7:59ece353eea2 84 }
omatthews 18:f5d26d3d532f 85
omatthews 30:055d856f05b5 86 void Heater::Set_ref(float R)
omatthews 19:fccdd7127f94 87 {
omatthews 19:fccdd7127f94 88 R_ref = R;
omatthews 19:fccdd7127f94 89 }
omatthews 30:055d856f05b5 90 void Heater::Set_D(float D)
omatthews 30:055d856f05b5 91 {
omatthews 25:09a315a59956 92 drive->write(D);
omatthews 26:f6c98b05ee85 93 guard->write(D*thermal.guard_drive_ratio);
omatthews 30:055d856f05b5 94 }
omatthews 0:4e33cc8171f4 95
justinbuckland 42:166d9bc7675e 96 float Heater::Get_D() const
omatthews 31:7c6f05326c4d 97 {
omatthews 31:7c6f05326c4d 98 return drive->read();
omatthews 31:7c6f05326c4d 99 }
omatthews 31:7c6f05326c4d 100
omatthews 30:055d856f05b5 101 int Heater::Get_i() const
omatthews 30:055d856f05b5 102 {
omatthews 30:055d856f05b5 103 return curr;
omatthews 30:055d856f05b5 104 }
omatthews 30:055d856f05b5 105 int Heater::Get_v() const
omatthews 30:055d856f05b5 106 {
omatthews 30:055d856f05b5 107 return v;
omatthews 30:055d856f05b5 108 }
omatthews 2:7f15386fcc90 109
omatthews 30:055d856f05b5 110 float Heater::Get_R() const
omatthews 30:055d856f05b5 111 {
omatthews 30:055d856f05b5 112 return R;
omatthews 30:055d856f05b5 113 }
omatthews 0:4e33cc8171f4 114
justinbuckland 42:166d9bc7675e 115 float Heater::Get_R_avg()
justinbuckland 42:166d9bc7675e 116 {
justinbuckland 42:166d9bc7675e 117 R_avg = R_acc / (float) n_acc;
justinbuckland 45:5f588512529b 118 R_var = (R2_acc*R2_acc - R_avg*R_avg) / n_acc
justinbuckland 42:166d9bc7675e 119 R_acc = 0;
justinbuckland 45:5f588512529b 120 R2_acc = 0;
justinbuckland 42:166d9bc7675e 121 n_acc = 0;
justinbuckland 42:166d9bc7675e 122 return R_avg;
justinbuckland 42:166d9bc7675e 123 }
justinbuckland 42:166d9bc7675e 124
justinbuckland 45:5f588512529b 125 float Heater::Get_R_var() // need to call Get_R_avg to calculate R_var before calling this function
justinbuckland 45:5f588512529b 126 {
justinbuckland 45:5f588512529b 127 return R_var;
justinbuckland 45:5f588512529b 128 }
justinbuckland 45:5f588512529b 129
omatthews 31:7c6f05326c4d 130 float Heater::Get_R_ref() const
omatthews 31:7c6f05326c4d 131 {
omatthews 31:7c6f05326c4d 132 return R_ref;
omatthews 31:7c6f05326c4d 133 }
omatthews 31:7c6f05326c4d 134
omatthews 31:7c6f05326c4d 135 float Heater::Get_error() const
omatthews 31:7c6f05326c4d 136 {
omatthews 31:7c6f05326c4d 137 return error;
omatthews 31:7c6f05326c4d 138 }
omatthews 31:7c6f05326c4d 139
omatthews 31:7c6f05326c4d 140 float Heater::Get_error_integrated() const
omatthews 31:7c6f05326c4d 141 {
omatthews 31:7c6f05326c4d 142 return error_integrated;
omatthews 31:7c6f05326c4d 143 }
omatthews 31:7c6f05326c4d 144
omatthews 30:055d856f05b5 145 void Heater::turn_on ()
omatthews 19:fccdd7127f94 146 {
omatthews 19:fccdd7127f94 147 *drive = 1;
omatthews 26:f6c98b05ee85 148 *guard = thermal.guard_drive_ratio;
omatthews 19:fccdd7127f94 149 }
omatthews 1:4435d407d827 150
omatthews 30:055d856f05b5 151 void Heater::turn_off ()
omatthews 19:fccdd7127f94 152 {
omatthews 19:fccdd7127f94 153 *drive = 0;
omatthews 19:fccdd7127f94 154 *guard = 0;
omatthews 19:fccdd7127f94 155 }