code for extended logging of resistance at a set set point temp
Dependencies: mbed
main.cpp
- Committer:
- AlexStokoe
- Date:
- 2018-09-24
- Revision:
- 0:c54aeef9c92d
File content as of revision 0:c54aeef9c92d:
#include "mbed.h" // thermal cycling settings #define N_CYCLES 1 // number of thermal cycles (ramp-hold-ramp-hold) #define R_SETPOINT_LOW 0.9800 // heater resistance at low temp R60 #define T_LOW_RAMP 10000 // low temperature ramp time (ms) #define T_LOW_HOLD 500 // low temperature hold time (ms) #define R_SETPOINT_HIGH 1.1 // heater resistance at high temp R95 #define T_HIGH_RAMP 10000 // high temperaure ramp time (ms) #define T_HIGH_HOLD 10000 // high temperature time (ms) #define T_HIGH_START 0000 // hotstart time(ms) // temperature measurement settings #define N_SAMPLES 1 // number of samples to acquire for I and V measurements #define N_ROLL_AVG 10 // rolling average for R values #define PULSE_WIDTH 5000 // heat or cool pulse width (us) #define MEAS_DELAY 50 // measurement delay after turning on FET (us) #define CAM_TRIG 20 // camera trigger pulse width (us) #define LOG_INTERVAL 500 // log file interval (ms) // ADC channels to read #define CH_A 1 // value of convst bus to read channel A only #define CH_AC 5 // value of convst bus to read channels A and C #define CH_ABCD 15 // value of convst bus to read all chanels simultaneously Serial pc(USBTX, USBRX); // tx, rx DigitalOut drive(p21); // drive FET DigitalOut yLED(p27); // yellow LED (drive on) DigitalOut gLED(p28); // green LED (power on) DigitalOut rLED(p26); // red LED (thermocycling in progress) DigitalOut camTrig(p24); // trigger camera AnalogIn battVolt(p19); AnalogIn auxVolt(p20); BusOut convt(p11, p12, p13, p14); SPI spi(p5, p6, p7); // mosi, miso, sclk DigitalOut cs(p8); // chip select DigitalIn busy(p9); DigitalOut reset(p10); Timer timer; LocalFileSystem local("local"); FILE *fp = fopen("/local/TEST_LOG.csv", "w"); // Open "test_log" on the local file system for writing float r = 0; float rAvg = 0; float rAcc = 0; float rSet; int nAcc = 0; int eTime; int logTime = 0; int iCycle = 0; char outString[100]; char buffer16[16]; int val_array[8]; const char dummy = 0; void logFile(void) { rAcc = rAcc + r; nAcc++; if (eTime > logTime) { // trigger camera camTrig = 1; wait_us(CAM_TRIG); camTrig = 0; // write data sprintf(outString, "$%1.6f$\n",rAcc/nAcc); // log data pc.printf("%s",outString); fprintf(fp, outString); logTime = logTime + LOG_INTERVAL; rAcc = 0; nAcc = 0; } } void readChannels (char buffer[16], int values[8]){ //simultaneously samples and reads into buffer short int val_array[8]; //send convert signal to channels convt = CH_AC; wait_us(1); convt = 0; //SPI(like) data transfer cs = 0; spi.write(&dummy, 1, buffer, 16); cs=1; //loop over bytes to add channel voltage values for (int i=0; i<8; i++){ val_array[i] = buffer[2*i]<<8 | buffer16[(2*i) + 1]; values [i] = val_array[i]; } r = (double)(val_array[5]-val_array[4])/(double)(val_array[1]-val_array[0]); } void tempControl(int endTime){ eTime = timer.read_ms(); while (eTime < endTime) { yLED = 1; drive = 1; wait_us(MEAS_DELAY); // wait for heater current to stabilise readChannels (buffer16, val_array); // read ADC channels and update r rAvg = ((N_ROLL_AVG-1)*rAvg + r)/N_ROLL_AVG; // calculate rolling average r // printf("hold r: %8.4f\r\n",r); if (rAvg > rSet) { drive = 0; // turn off heater if setpoint resistance is exceeded yLED = 0; } // printf("set r: %8.4f\r\n",r); logFile(); wait_us(PULSE_WIDTH); //wait until pulse_width (us) has elapsed eTime = timer.read_ms(); } } void tempControlRamp(float setStartR, float setEndR, int endTime){ float setRate; int startTime; startTime = timer.read_ms(); setRate = (setEndR - setStartR)/(endTime - startTime); eTime = startTime; while (eTime < endTime) { rSet = setStartR + setRate*(eTime - startTime); yLED = 1; drive = 1; wait_us(MEAS_DELAY); // wait for heater current to stabilise readChannels (buffer16, val_array); // read ADC channels and update r rAvg = ((N_ROLL_AVG-1)*rAvg + r)/N_ROLL_AVG; // measure r if (rAvg > rSet) { drive = 0; // turn off heater if setpoint resistance is exceeded yLED = 0; } // printf("ramp r: %8.4f\r\n",r); logFile(); wait_us(PULSE_WIDTH); //wait until pulse_width (us) has elapsed eTime = timer.read_ms(); } } int main() { int endTime = 0; rLED = 0; yLED = 0; gLED = 0; drive = 0; pc.baud(115200); //Reset ADC sequence reset = 1; wait_ms(1); reset = 0; //set SPI serial to 2MHz, 16 bit data transfer, mode 2 (clock normally high, data preceeding clock cycle) spi.format(8,2); spi.frequency(2000000); spi.set_default_write_value(0x00); cs = 1; rLED = 1; // thermal cycling in progress yLED = 0; // heater on gLED = 1; // microprocessor power on sprintf(outString,"$r$\n"); pc.printf("%s", outString); fprintf(fp, outString); timer.start(); // optional hot start: additional HIGH temperature time at start if (T_HIGH_START > 0) { endTime = T_HIGH_START; rSet = R_SETPOINT_HIGH; tempControl(endTime); } // loop forever while(1) { // hold at HIGH temperature endTime = endTime + T_HIGH_HOLD; rSet = R_SETPOINT_HIGH; tempControl(endTime); } // extinguish rLED (thermocycling complete), ensure heater is off and close log file for access drive = 0; rLED = 0; logTime = 0; logFile(); fclose(fp); }