implement 2 point calibration and resistance calculation
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295
include/ec.h
295
include/ec.h
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@ -7,9 +7,6 @@
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#define EC_PIN_RELAY_CALIBRATION 26
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#define EC_PIN_RELAY_RANGE 25
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#define EC_CALIBRATION_RESISTOR_NC 100000
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#define EC_CALIBRATION_RESISTOR_NO 1000
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#define EC_PIN_ADC 4
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#define EC_PIN_FREQ 5
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@ -17,37 +14,299 @@
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#define EC_RESOLUTION 8
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#define EC_FREQUENCY 5000
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#define EC_ARRAY_SIZE 1024
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uint16_t ec_array[EC_ARRAY_SIZE];
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uint16_t ec_array_pos=0;
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unsigned long last_read_ec=0;
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#define EC_READ_INTERVAL 1
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#define EC_ARRAY_SIZE 128
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uint16_t ec_array_rangeLow[EC_ARRAY_SIZE];
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uint16_t ec_array_rangeHigh[EC_ARRAY_SIZE];
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uint16_t ec_array_pos=EC_ARRAY_SIZE*2;
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#define EC_MEASUREMENT_INTERVAL 10000 //complete filtered measurement every x ms
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//One filtered measurement takes EC_READ_INTERVAL*EC_ARRAY_SIZE*2
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#define EC_READ_INTERVAL 5 //interval of reading adc value inside a measurement
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float ec_calib_rangeLow_Rlow=0; //adc value for low value resistor on low resistor value range
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float ec_calib_rangeLow_Rhigh=0; //adc value for high value resistor on low resistor value range
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float ec_calib_rangeHigh_Rlow=0; //adc value for low value resistor on high resistor value range
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float ec_calib_rangeHigh_Rhigh=0; //adc value for high value resistor on high resistor value range
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const float ec_calibresistor_low=990; //value of low value calibration resistor. Low is Relay NO
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const float ec_calibresistor_high=9943; //value of high value calibration resistor. HIGH is Relay NC
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unsigned long ec_last_calibration=0; //millis of last calibration
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#define EC_CALIBRATION_VALID_TIME 120000 //time in ms a calibration is valid for
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#define EC_RELAY_SWITCH_SETTLETIME 500 //time until voltage of ec circuit has settled
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unsigned long ec_last_change_relay=0; //millis of last relay change
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enum ECState{IDLE,CALIBRATELOW,CALIBRATEHIGH,MEASURE};
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ECState ecstate=CALIBRATELOW;
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bool ec_measurementReady();
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void ec_startMeasurement();
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void ec_setRange(bool);
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void ec_connectProbe(bool);
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void ec_setCalibration(bool calib);
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void ec_releaseRelay();
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void ec_startCalibration();
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void ec_checkIfSettleTimeOK();
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float ec_getResistance(float adc,float caliblow,float resistorlow,float calibhigh,float resistorhigh);
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void ec_setup() {
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pinMode(EC_PIN_ADC,INPUT);
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ledcSetup(EC_PWM_CH, EC_FREQUENCY, EC_RESOLUTION);
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ledcAttachPin(EC_PIN_FREQ, EC_PWM_CH);
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ledcWrite(EC_PWM_CH, 127);
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ledcWrite(EC_PWM_CH, 127); //50% duty cycle
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pinMode(EC_PIN_RELAY_PROBE,OUTPUT); //LOW=Calibration/idle, HIGH=Probe connected
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pinMode(EC_PIN_RELAY_CALIBRATION,OUTPUT); //LOW=NC Calibration Resistor, HIGH=NO Calib. Res.
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pinMode(EC_PIN_RELAY_RANGE,OUTPUT); //LOW=NC Range Resistor, HIGH=NO Range Resistor
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ec_releaseRelay();
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ec_startCalibration();
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}
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void ec_loop(unsigned long loopmillis) {
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static unsigned long last_measurement_ec=0;
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static unsigned long last_read_ec=0;
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switch (ecstate) {
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case IDLE:
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if (loopmillis>ec_last_calibration+EC_CALIBRATION_VALID_TIME) { //calibration needed
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ec_last_calibration=loopmillis;
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ecstate=CALIBRATELOW;
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ec_startCalibration();
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}
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if (loopmillis>last_measurement_ec+EC_MEASUREMENT_INTERVAL && ecstate==IDLE) { //start measurement if idle
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last_measurement_ec=loopmillis;
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ec_startMeasurement();
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ec_connectProbe(true);
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ecstate=MEASURE;
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Serial.println("EC Take Measurement");
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}
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break;
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case CALIBRATELOW:
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if (ec_measurementReady()) {
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//Serial.println("EC CALIBRATELOW measurement ready");
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//save measurement
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ec_calib_rangeLow_Rlow=getMean(ec_array_rangeLow,EC_ARRAY_SIZE);
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ec_calib_rangeHigh_Rlow=getMean(ec_array_rangeHigh,EC_ARRAY_SIZE);
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//ec_checkIfSettleTimeOK();
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//Switch to High calibration
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ecstate=CALIBRATEHIGH;
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ec_setCalibration(HIGH);
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ec_setRange(LOW);
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ec_startMeasurement();
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//Serial.println("EC Start calibration high");
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}
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break;
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case CALIBRATEHIGH:
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if (ec_measurementReady()) {
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//Serial.println("EC CALIBRATEHIGH measurement ready");
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//save measurement
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ec_calib_rangeLow_Rhigh=getMean(ec_array_rangeLow,EC_ARRAY_SIZE);
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ec_calib_rangeHigh_Rhigh=getMean(ec_array_rangeHigh,EC_ARRAY_SIZE);
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//ec_checkIfSettleTimeOK();
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//Serial.println("EC Release Relay");
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ec_releaseRelay();
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ecstate=IDLE;
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/*
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Serial.println("EC Calibration done");
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Serial.print("ec_calib_rangeLow_Rlow="); Serial.println(ec_calib_rangeLow_Rlow);
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Serial.print("ec_calib_rangeHigh_Rlow="); Serial.println(ec_calib_rangeHigh_Rlow);
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Serial.print("ec_calib_rangeLow_Rhigh="); Serial.println(ec_calib_rangeLow_Rhigh);
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Serial.print("ec_calib_rangeHigh_Rhigh="); Serial.println(ec_calib_rangeHigh_Rhigh);
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*/
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Serial.println("EC Calibration Result: ");
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Serial.print(ec_calib_rangeLow_Rlow);
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Serial.print(", "); Serial.print(ec_calib_rangeHigh_Rlow);
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Serial.print(", "); Serial.print(ec_calib_rangeLow_Rhigh);
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Serial.print(", "); Serial.println(ec_calib_rangeHigh_Rhigh);
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}
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break;
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case MEASURE:
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if (ec_measurementReady()) {
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ec_releaseRelay();
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float adc_rangelow=getMean(ec_array_rangeLow,EC_ARRAY_SIZE);
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float adc_rangehigh=getMean(ec_array_rangeHigh,EC_ARRAY_SIZE);
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Serial.println();
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float resistance_rangelow=ec_getResistance(adc_rangelow,ec_calib_rangeLow_Rlow,ec_calibresistor_low,ec_calib_rangeLow_Rhigh,ec_calibresistor_high);
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Serial.print("Range Low: ADC="); Serial.print(adc_rangelow); Serial.print(", resistance="); Serial.println(resistance_rangelow);
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Serial.println();
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float resistance_rangehigh=ec_getResistance(adc_rangehigh,ec_calib_rangeHigh_Rlow,ec_calibresistor_low,ec_calib_rangeHigh_Rhigh,ec_calibresistor_high);
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Serial.print("Range High: ADC="); Serial.print(adc_rangehigh); Serial.print(", resistance="); Serial.println(resistance_rangehigh);
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ecstate=IDLE;
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}
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break;
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}
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if (loopmillis>last_read_ec+EC_READ_INTERVAL && ec_array_pos/2<EC_ARRAY_SIZE) { //take reading into array if measurement running
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last_read_ec=loopmillis;
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//flag_print= ec_array_pos==EC_ARRAY_SIZE;
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//ec_array_pos%=EC_ARRAY_SIZE;
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if (ec_array_pos<EC_ARRAY_SIZE){ //low range
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ec_setRange(LOW);
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}else{ //high range
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ec_setRange(HIGH);
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}
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if (loopmillis>ec_last_change_relay+EC_RELAY_SWITCH_SETTLETIME) { //values have settled
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uint16_t value=analogRead(EC_PIN_ADC);
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if (ec_array_pos<EC_ARRAY_SIZE){ //low range
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ec_array_rangeLow[ec_array_pos%EC_ARRAY_SIZE]=value;
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}else{ //high range
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ec_array_rangeHigh[ec_array_pos%EC_ARRAY_SIZE]=value;
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}
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/*
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if (ec_array_pos==0) {
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Serial.println(""); Serial.print("Lowrange:");
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}
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if (ec_array_pos==EC_ARRAY_SIZE) {
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Serial.println(""); Serial.print("Highrange:");
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}
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Serial.print(value); Serial.print(" ");
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if (ec_array_pos==EC_ARRAY_SIZE*2-1) {
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Serial.println("");
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}
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*/
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ec_array_pos++;
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}
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}
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}
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void ec_startCalibration() {
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//Switch to Low calibration
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ec_setCalibration(LOW);
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ec_setRange(LOW);
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ec_startMeasurement();
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Serial.println("EC Started Calibration");
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}
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void ec_startMeasurement() {
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ec_array_pos=0;
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}
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bool ec_measurementReady(){
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if (ec_array_pos>=EC_ARRAY_SIZE*2) { //reached end of both arrays
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return true;
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}else{
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return false;
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}
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}
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void ec_setRange(bool range) {
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//range low means low resistor value -> NO -> relay High
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bool val=digitalRead(EC_PIN_RELAY_RANGE);
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if (val!=!range) { //write only if different
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digitalWrite(EC_PIN_RELAY_RANGE,!range);
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ec_last_change_relay=millis();
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}
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}
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void ec_connectProbe(bool relay) {
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bool val=digitalRead(EC_PIN_RELAY_PROBE);
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if (val!=relay) { //write only if different
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digitalWrite(EC_PIN_RELAY_PROBE,relay);
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ec_last_change_relay=millis();
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}
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}
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void ec_setCalibration(bool calib) {
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//calib low means low resistor value -> NO -> relay high
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ec_connectProbe(false);
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bool val=digitalRead(EC_PIN_RELAY_CALIBRATION);
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if (val!=!calib) { //write only if different
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digitalWrite(EC_PIN_RELAY_CALIBRATION,!calib);
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ec_last_change_relay=millis();
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}
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}
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void ec_releaseRelay() {
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digitalWrite(EC_PIN_RELAY_PROBE,LOW);
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digitalWrite(EC_PIN_RELAY_CALIBRATION,LOW);
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digitalWrite(EC_PIN_RELAY_RANGE,LOW);
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ec_last_change_relay=millis();
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}
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void ec_loop(unsigned long loopmillis, unsigned long pInterval) {
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if (loopmillis>last_read_ec+pInterval) {
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last_read_ec=loopmillis;
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ec_array_pos++;
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flag_print= ec_array_pos==EC_ARRAY_SIZE;
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ec_array_pos%=EC_ARRAY_SIZE;
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ec_array[ec_array_pos]=analogRead(EC_PIN_ADC);
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//Serial.print(ec_array[ec_array_pos]); Serial.print(" ");
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void ec_checkIfSettleTimeOK() {
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/*
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Serial.print("ec_array_rangeLow[0]="); Serial.println(ec_array_rangeLow[0]);
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Serial.print("rangeLow min="); Serial.println(getMin(ec_array_rangeLow,EC_ARRAY_SIZE));
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Serial.print("rangeLow max="); Serial.println(getMax(ec_array_rangeLow,EC_ARRAY_SIZE));
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*/
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if (ec_array_rangeLow[0]<=getMin(ec_array_rangeLow,EC_ARRAY_SIZE) || ec_array_rangeLow[0]>=getMax(ec_array_rangeLow,EC_ARRAY_SIZE)){
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//is first value the highest or lowest?
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Serial.println("Warning: EC_RELAY_SWITCH_SETTLETIME might be too low! (ec_calib_rangeLow_Rlow)");
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}
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/*
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Serial.print("ec_array_rangeHigh[0]="); Serial.println(ec_array_rangeHigh[0]);
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Serial.print("rangeHigh min="); Serial.println(getMin(ec_array_rangeHigh,EC_ARRAY_SIZE));
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Serial.print("rangeHigh max="); Serial.println(getMax(ec_array_rangeHigh,EC_ARRAY_SIZE));
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*/
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if (ec_array_rangeHigh[0]<=getMin(ec_array_rangeHigh,EC_ARRAY_SIZE) || ec_array_rangeHigh[0]>=getMax(ec_array_rangeHigh,EC_ARRAY_SIZE)){
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//is first value the highest or lowest?
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Serial.println("Warning: EC_RELAY_SWITCH_SETTLETIME might be too low! (ec_array_rangeHigh)");
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}
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}
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float ec_getResistance(float adc,float caliblow,float resistorlow,float calibhigh,float resistorhigh)
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{
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//adc = adc reading to calculate resistance for
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//caliblow = adc value from calibration. Low resistance
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//resistorlow = actual resistor value. Low resistance
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//calibhjgh = adc value from calibration. High resistance
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//resistorhigh = actual resistor value. High resistance
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//y=mx+a;
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//resistorlow=m*caliblow+a;
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//resistorhigh=m*calibhigh+a;
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//linear interpolation interpolate
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double m=(resistorhigh-resistorlow)/(calibhigh-caliblow);
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float a=resistorlow-m*caliblow;
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Serial.print("m="); Serial.println(m);
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Serial.print("a="); Serial.println(a);
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return m*adc+a;
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}
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#endif
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