1 files changed, 78 insertions, 0 deletions
diff --git a/os/various/pid.h b/os/various/pid.h
new file mode 100644
index 0000000..49ccd6f
--- /dev/null
+++ b/os/various/pid.h
@@ -0,0 +1,78 @@
+#ifndef PID_h
+#define PID_h
+
+#include "chtypes.h"
+
+//Constants used in some of the functions below
+#define PID_AUTOMATIC 1
+#define PID_MANUAL 0
+#define PID_DIRECT 0
+#define PID_REVERSE 1
+#define PID_ON_M 0
+#define PID_ON_E 1
+
+
+typedef struct {
+
+    float kp;     // * (P)roportional Tuning Parameter
+    float ki;     // * (I)ntegral Tuning Parameter
+    float kd;     // * (D)erivative Tuning Parameter
+
+    float dispKp; // * we'll hold on to the tuning parameters in user-entered 
+    float dispKi; //   format for display purposes
+    float dispKd; //
+
+    int direction;
+    int pOn;
+
+    float *input;              // * Pointers to the Input, Output, and Setpoint variables
+    float *output;             //   This creates a hard link between the variables and the 
+    float *setPoint;           //   PID, freeing the user from having to constantly tell us
+                               //   what these values are.  with pointers we'll just know.
+    unsigned long lastTime;
+    float outputSum;
+    float lastInput;
+
+    unsigned long sampleTime;
+    float outMin;
+    float outMax;
+
+    bool inAuto;
+    bool pOnE;
+
+} pidc_t;
+
+
+//commonly used functions **************************************************************************
+void pid_create(pidc_t* p, float* Input, float* Output, float* Setpoint,  // * constructor.  links the PID to the Input, Output, and 
+                float Kp, float Ki, float Kd, int POn, int Direction);    //   Setpoint.  Initial tuning parameters are also set here.
+                                                                          //   (overload for specifying proportional mode)
+
+void pid_setMode(pidc_t* p, int mode);                 // * sets PID to either Manual (0) or Auto (non-0)
+
+bool pid_compute(pidc_t* p);               // * performs the PID calculation.  it should be
+                                           //   called every time loop() cycles. ON/OFF and
+                                           //   calculation frequency can be set using SetMode
+                                           //   SetsampleTime respectively
+
+void pid_setOutputLimits(pidc_t* p, float Min, float Max); // * clamps the output to a specific range. 0-255 by default, but
+                                                           //   it's likely the user will want to change this depending on
+                                                           //   the application
+
+
+
+//available but not commonly used functions ********************************************************
+void pid_setTunings(pidc_t* p, float Kp, float Ki, float Kd, int POn);  // * While most users will set the tunings once in the 
+                                                                        //   constructor, this function gives the user the option
+                                                                        //   of changing tunings during runtime for Adaptive control
+
+void pid_setDirection(pidc_t* p, int Direction);  // * Sets the Direction, or "Action" of the controller. DIRECT
+                                                  //   means the output will increase when error is positive. REVERSE
+                                                  //   means the opposite.  it's very unlikely that this will be needed
+                                                  //   once it is set in the constructor.
+void pid_setSampleTime(pidc_t* p, int NewSampleTime);  // * sets the frequency, in Milliseconds, with which 
+                                                       //   the PID calculation is performed.  default is 100
+
+void pid_initialize(pidc_t* p);
+
+#endif