168 lines
4.5 KiB
C++
168 lines
4.5 KiB
C++
/*
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* Detector Building
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* Code by Anthony Wang
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* Ladue High School Science Olympiad
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*/
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/*
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* TODO:
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* BUG FIXING: Expect bugs!
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*/
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// Constants
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const int LED_R = 4, LED_G = 3, LED_B = 2, THERM = 0; // Device component pins
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const double R_k = 10000, V_in = 5, analog_max = 1023; // Device constants
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// Temperature conversions
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inline double f2c(double f) { return (f - 32) * 5 / 9; } // Fahrenheit to Celsius
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inline double c2f(double c) { return c * 9 / 5 + 32; } // Celsius to Fahrenheit
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inline double k2c(double k) { return k - 273.15; } // Kelvin to Celsius
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inline double c2k(double c) { return c + 273.15; } // Celsius to Kelvin
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inline double f2k(double f) { return c2k(f2c(f)); } // Fahrenheit to Kelvin
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inline double k2f(double k) { return c2f(k2c(k)); } // Kelvin to Fahrenheit
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// Analog to digital conversion
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inline double a2d(int a) { return V_in * a / analog_max; }
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inline int d2a(double d) { return d * analog_max / V_in; }
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// Utility functions
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// No C++ standard library :(
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void sort(int& a[], int n) {
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// Bubble sort
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// Slow but n < 30 so OK
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// Too lazy to implement a fast sort
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for (int i = 0; i < n; i++) {
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for (int j = 0; j < n - 1; j++) {
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if (a[j] > a[j + 1]) {
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int tmp = a[j];
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a[j] = a[j + 1];
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a[j + 1] = tmp;
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}
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}
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}
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}
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// Calibration data
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const int n = 3, m = n / 3; // Number of data points, MUST be multiple of 3
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double V[n] = { 2.5, 3.26, 3.96 }; // Voltage measurements
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double T[n] = { 25, 39.15, 60 }; // Temperature measurements
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double V_mid[m]; // Stores each piecewise segment for binary search
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double A[m], B[m], C[m]; // Coefficients for each piecewise component
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// Calculations
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// Steinhart-hart stuff
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void calculate() {
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sort(V, n);
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sort(T, n);
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double R[n], L[n], Y[n], G[n];
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for (int i = 0; i < n; i++) R[i] = R_k * (V_in / V[i] - 1);
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for (int i = 0; i < n; i++) L[i] = log(R[i]);
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for (int i = 0; i < n; i++) Y[i] = 1 / c2k(T[i]);
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for (int i = 0; i < n; i += 3) {
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G[i + 1] = (Y[i + 1] - Y[i]) / (L[i + 1] - L[i]);
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G[i + 2] = (Y[i + 2] - Y[i]) / (L[i + 2] - L[i]);
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}
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for (int i = 0; i < n; i += 3) { // Don't ask how this works
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C[i / 3] = (G[i + 2] - G[i + 1]) / (L[i + 2] - L[i + 1]) / (L[i] + L[i + 1] + L[i + 2]);
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B[i / 3] = G[i + 1] - C[i / 3] * (L[i] * L[i] + L[i] * L[i + 1] + L[i + 1] * L[i + 1]);
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A[i / 3] = Y[i] - L[i] * (B[i / 3] + L[i] * L[i] * C[i / 3]);
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}
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for (int i = 0; i < n; i += 3) V_mid[i / 3] = (i ? (V[i - 1] + V[i]) / 2 : V[i]);
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}
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// Arduino stuff
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void blink(int pin) {
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digitalWrite(pin, HIGH);
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delay(1000);
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digitalWrite(pin, LOW);
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}
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void setup() {
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Serial.begin(9600);
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pinMode(LED_R, OUTPUT);
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pinMode(LED_G, OUTPUT);
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pinMode(LED_B, OUTPUT);
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// blink(LED_R);
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// blink(LED_G);
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// blink(LED_B);
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// Debug stuff
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/*for (int i = 0; i < m; i++) {
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Serial.print("Segment lower bound: ");
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Serial.print(i ? V_mid[i - 1] : 0);
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Serial.print(" Segment upper bound: ");
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Serial.print(V_mid[i]);
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Serial.print(" A: ");
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Serial.print(A[i], 12);
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Serial.print(" B: ");
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Serial.print(B[i], 12);
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Serial.print(" C: ");
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Serial.print(C[i], 12);
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Serial.println();
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}*/
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}
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// Main loop
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void loop() {
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int V_raw = analogRead(THERM); // Read in raw analog value
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double V_out = a2d(V_raw); // Convert analog to digital
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double R_t = R_k * (V_in / V_out - 1); // Thermistor resistance
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int s = 0;
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while (s < m && V_out > V_mid[s + 1]) s++; // Find correct segment
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double logR_t = log(R_t);
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double K = 1.0 / (A[s] + B[s] * logR_t + C[s] * logR_t * logR_t * logR_t); // Steinhart-hart
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double C = k2c(K);
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double F = c2f(C);
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// LED stuff
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if (C <= 25) {
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digitalWrite(LED_R, LOW);
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digitalWrite(LED_G, LOW);
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digitalWrite(LED_B, HIGH);
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}
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else if (C <= 50) {
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digitalWrite(LED_R, LOW);
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digitalWrite(LED_G, HIGH);
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digitalWrite(LED_B, LOW);
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}
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else if (C <= 75) {
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digitalWrite(LED_R, HIGH);
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digitalWrite(LED_G, LOW);
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digitalWrite(LED_B, LOW);
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}
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else {
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digitalWrite(LED_R, HIGH);
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digitalWrite(LED_G, HIGH);
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digitalWrite(LED_B, HIGH);
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}
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// Output voltage, temperature
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Serial.print("Raw analog reading: ");
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Serial.print(V_raw);
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Serial.print(" Voltage (V): ");
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Serial.print(V_out);
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Serial.print(" Temperature (°C): ");
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Serial.print(C);
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Serial.print(" Temperature (°F): "); // For reference
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Serial.print(F);
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// Debug stuff
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/*Serial.print(" Segment lower bound: ");
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Serial.print(s ? V_mid[s - 1] : 0);
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Serial.print(" Segment upper bound: ");
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Serial.print(V_mid[s]);*/
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Serial.println();
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delay(500);
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}
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