fix temp sensor kind of

main.cpp

@@ -22,13 +22,13 @@ var names: snake_case
 //thermistor equation is R=R_0*e^(1/T-1/T_0)
 
 class CustomArray {
-    int* items;    
+    float* items;    
     int size;
 
     public:
     CustomArray(int s = MAX_STORED_VALUES) {
         size = s;
-        items = (int*) malloc(size * sizeof(int));
+        items = (float*) malloc(size * sizeof(int));
         for (int i = 0; i < size; i++ ) items[i] = 0;
     }
 
@@ -40,9 +40,9 @@ class CustomArray {
         items[0] = item;
     }
 
-    int getElement(int index) { return items[index]; }
-    int getSum() {
-        int sum = 0;
+    float getElement(int index) { return items[index]; }
+    float getSum() {
+        float sum = 0;
 
         for (int i = 0; i < MAX_STORED_VALUES; i++ ) {
             sum += items[i];
@@ -60,9 +60,12 @@ class PID {
     private:
         int kp, ki, kd, //PID
             pwm_pin, thermistor_pin, //thermistor
+            index //misc
+        ;
+        float desired_temp, temp, //temperature
             thermistor_resistance, voltage_devider_resistance, thermistor_beta, thermistor_ref_temp, //thermistor
-            desired_temp, temp, //temperature
-            index; //misc
+            adc_conversion_factor
+        ;
         bool on;
         CustomArray error_array;
 
@@ -71,14 +74,14 @@ class PID {
             int index,
             int pwm_pin,
             int thermistor_pin,
-            int desired_temp = 0,
+            float desired_temp = 0,
             int kp = 1000,
             int ki = 100,
             int kd = 10,
-            int thermistor_resistance = 100000,
-            int thermistor_beta = 3950,
-            int thermistor_ref_temp = 25, //C 
-            int voltage_devider_resistance = 100000
+            float thermistor_resistance = 100000,
+            float thermistor_beta = 3950,
+            float thermistor_ref_temp = 25, //C 
+            float voltage_devider_resistance = 100000
         )  {
             error_array = CustomArray();
 
@@ -88,35 +91,37 @@ class PID {
             this->thermistor_pin = thermistor_pin;
             this->thermistor_resistance = thermistor_resistance;
             this->thermistor_beta = thermistor_beta;
+            this->thermistor_ref_temp = thermistor_ref_temp + 273;
             this->voltage_devider_resistance = voltage_devider_resistance;
             this->desired_temp = desired_temp;
             this->index = index;
+            this->adc_conversion_factor = 3.3f / (1 << 12);
 
             measureTemp();
         }
 
-        int getTemp() {
+        float getTemp() {
             return this->temp;
         }
 
-        int measureTemp() {
-            //adc_select_input(thermistor_pin);
+        float measureTemp() {
+            adc_select_input(thermistor_pin);
             uint16_t result = adc_read();
-            uint16_t v_slash_vin = 2<<15 / result;
-            uint16_t r = v_slash_vin * voltage_devider_resistance / (1 / (1-v_slash_vin));
+            float v = (float)result * adc_conversion_factor; //calculate ratio of measured voltage and max voltage
+            float r = v / (3.3f - v) * voltage_devider_resistance;
 
-            int T = 1/(1/thermistor_beta * log(r/thermistor_resistance) + 1/thermistor_ref_temp);
+            float T = 1/(1/thermistor_beta * log(r/thermistor_resistance) + 1/thermistor_ref_temp) - 273;
 
-            this->temp = 10;
-
-            return this->temp;
+            this->temp = T;
+            return T;
         }
            
-        int calulatePid( int x ) {
-            int e = desired_temp-x; 
+        int calulatePid(float desired = -100) {
+            if (desired != -100) desired_temp = desired;
+            float e = desired_temp-temp; 
 
-            int e_dot = (e - error_array.getElement(0)) / POLL_PERIOD;
-            int e_int = error_array.getSum() * POLL_PERIOD;
+            float e_dot = (e - error_array.getElement(0)) / POLL_PERIOD;
+            float e_int = error_array.getSum() * POLL_PERIOD;
 
             return e * kp + e_dot * kd + e_int * ki;
         }
@@ -143,8 +148,9 @@ int main()
     gpio_put(13, 1);
 
     while (true) {
-        printf("%f\n", test_pid.getTemp());
-        //printf("asdf");
+        float val = test_pid.measureTemp();
+        float pid = test_pid.calulatePid(80);
+        printf("temp: %f\npid: %f", val, pid); 
         sleep_ms(500);
     }
 }