start writing thermistor code

CMakeLists.txt

@@ -46,7 +46,8 @@ pico_enable_stdio_usb(main 1)
 
 # Add the standard library to the build
 target_link_libraries(main
-        pico_stdlib)
+        pico_stdlib
+        hardware_adc)
 
 # Add the standard include files to the build
 target_include_directories(main PRIVATE

main.cpp

@@ -2,26 +2,32 @@
 #include <stdlib.h> 
 #include <array>
 #include "pico/stdlib.h"
+#include <math.h>
+#include "hardware/gpio.h"
+#include "hardware/adc.h"
 
 using namespace std;
 
 #define POLL_PERIOD 50 //time between polls (ms)
 #define MAX_STORED_VALUES 10 //number of stored values to calculate e_dot and e_dot_dot values
+#define REFERENCE_VOLTAGE 3.3 //reference voltage for the adc converter
 
 /*
-trying to keep the code clean, so some conventions:
+trying to keep the code clean, so some conventions: 
 classes: PascalCase
 function: camelCase
 var names: snake_case
 */
 
+//thermistor equation is R=R_0*e^(1/T-1/T_0)
+
 class CustomArray {
     int* items;    
     int size;
 
     public:
-    CustomArray() {
-        size = MAX_STORED_VALUES;
+    CustomArray(int s = MAX_STORED_VALUES) {
+        size = s;
         items = (int*) malloc(size * sizeof(int));
         for (int i = 0; i < size; i++ ) items[i] = 0;
     }
@@ -52,14 +58,54 @@ class CustomArray {
 
 class PID {
     private:
-        int kp, ki, kd, pwm_pin, thermistor_pin, index, desired_temp;
+        int kp, ki, kd, //PID
+            pwm_pin, thermistor_pin, //thermistor
+            thermistor_resistance, voltage_devider_resistance, thermistor_beta, thermistor_ref_temp, //thermistor
+            desired_temp, temp, //temperature
+            index; //misc
         bool on;
         CustomArray error_array;
 
     public:
-        PID(int kp) {
+        PID(
+            int index,
+            int pwm_pin,
+            int thermistor_pin,
+            int 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
+        )  {
             error_array = CustomArray();
+
             this->kp = kp;
+            this->ki = ki;
+            this->kd = kd;
+            this->thermistor_pin = thermistor_pin;
+            this->thermistor_resistance = thermistor_resistance;
+            this->thermistor_beta = thermistor_beta;
+            this->voltage_devider_resistance = voltage_devider_resistance;
+            this->desired_temp = desired_temp;
+            this->index = index;
+
+            measureTemp();
+        }
+
+        int getTemp() {
+            return this->temp;
+        }
+
+        int measureTemp() {
+            //adc_select_input(thermistor_pin);
+            //uint16_t result = adc_read();
+
+            this->temp = 10;
+
+            return this->temp;
         }
 
         int calulatePid( int x ) {
@@ -67,27 +113,34 @@ class PID {
 
             int e_dot = (e - error_array.getElement(0)) / POLL_PERIOD;
             int e_int = error_array.getSum() * POLL_PERIOD;
-        
 
             return e * kp + e_dot * kd + e_int * ki;
         }
 };
 
 void init() {
+    stdio_init_all();
+    adc_init();
+
     gpio_init(25);
+    gpio_init(13);
     gpio_set_dir(25, GPIO_OUT);
+    gpio_set_dir(13, GPIO_OUT);
+
+    adc_gpio_init(27);
 }
 
 int main()
 {
-    stdio_init_all();
+    init();
 
+    PID test_pid = PID(0, 6, 1);
+
+    gpio_put(13, 1);
 
     while (true) {
-        //printf("Hello, world!\n");
-        gpio_put(25, 0);
-        sleep_ms(250);
-        gpio_put(25, 1);
-        sleep_ms(250);
+        printf("%f\n", test_pid.getTemp());
+        //printf("asdf");
+        sleep_ms(500);
     }
 }