Initial Commit

README.md

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+# Reflow Plate
+Custom Reflow Plate inspired by [UnexpectedMaker
+ReflowMaster](https://github.com/UnexpectedMaker/ReflowMaster)
+[Pro](https://reflowmasterpro.com)
+using [PID](https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%E2%80%93derivative_controller)
+to control a simple grill.

src/pid.cpp

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+const float k_p = 1.0;
+const float k_i = 3.0;
+const float k_d = 0.2;
+const float tick_millis = 30'000;
+
+float target;
+float measured;
+float error;
+float error_last;
+float output;
+float i;
+float d;
+
+unsigned long time_last_millis;
+unsigned long time_cur_millis;
+unsigned long time_delta_millis;
+
+float pid(float error, float error_last, unsigned long delta){
+    float p = k_p * error;
+    float i = i + (k_i * delta * error);
+    float d = k_d * (error - error_last) / delta;
+    return p+i+d;
+}
+
+void setup(){
+    time_last_millis = millis();
+}
+
+void loop(){
+    time_cur_millis = millis();
+    time_delta_millis = time_cur_millis - time_last_millis;
+    if (time_delta_millis > tick_millis) {
+        time_last_millis = time_cur_millis;
+        error_last = error;
+        error = target - measured;
+        output = pid(error, error_last, time_delta_millis);
+    }
+}