Adding MagneticSensorPWM

This implementation has been tested with the AS5048a PWM output.  It follows an almost identical format to the existing MagneticSensorAnalog implementation.

Author: jordancormack

src/SimpleFOC.h

@@ -102,6 +102,7 @@ void loop() {
 #include "sensors/MagneticSensorSPI.h"
 #include "sensors/MagneticSensorI2C.h"
 #include "sensors/MagneticSensorAnalog.h"
+#include "sensors/MagneticSensorPWM.h"
 #include "sensors/HallSensor.h"
 #include "drivers/BLDCDriver3PWM.h"
 #include "drivers/BLDCDriver6PWM.h"

src/sensors/MagneticSensorPWM.cpp

@@ -0,0 +1,66 @@
+#include "MagneticSensorPWM.h"
+
+/** MagneticSensorPWM(uint8_t _pinPWM, int _min, int _max)
+ * @param _pinPWM  the pin that is reading the pwm from magnetic sensor
+ * @param _min_raw_count  the smallest expected reading
+ * @param _max_raw_count  the largest expected reading
+ */
+MagneticSensorPWM::MagneticSensorPWM(uint8_t _pinPWM, int _min_raw_count, int _max_raw_count){
+
+    pinPWM = _pinPWM;
+
+    cpr = _max_raw_count - _min_raw_count;
+    min_raw_count = _min_raw_count;
+    max_raw_count = _max_raw_count;
+    
+    pinMode(pinPWM, INPUT);
+}
+
+
+void MagneticSensorPWM::init(){
+    
+    // velocity calculation init
+    angle_prev = 0;
+    velocity_calc_timestamp = _micros();
+
+    // full rotations tracking number
+    full_rotation_offset = 0;
+    raw_count_prev = getRawCount();
+}
+
+// get current angle (rad) 
+float MagneticSensorPWM::getAngle(){
+
+    // raw data from sensor
+    raw_count = getRawCount();
+    
+    int delta = raw_count - raw_count_prev;
+    // if overflow happened track it as full rotation
+    if(abs(delta) > (0.8*cpr) ) full_rotation_offset += delta > 0 ? -_2PI : _2PI;
+
+    float angle = full_rotation_offset + ( (float) (raw_count) / (float)cpr) * _2PI;
+
+    // calculate velocity here
+    long now = _micros();
+    float Ts = (now - velocity_calc_timestamp)*1e-6;
+    // quick fix for strange cases (micros overflow)
+    if(Ts <= 0 || Ts > 0.5) Ts = 1e-3;
+    velocity = (angle - angle_prev)/Ts;
+
+    // save variables for future pass
+    raw_count_prev = raw_count;
+    angle_prev = angle;
+    velocity_calc_timestamp = now;
+
+    return angle;
+}
+
+//  get velocity (rad/s)
+float MagneticSensorPWM::getVelocity(){
+  return velocity;
+}
+
+// read the raw counter of the magnetic sensor
+int MagneticSensorPWM::getRawCount(){
+	return pulseIn(pinPWM,HIGH);
+}

src/sensors/MagneticSensorPWM.h

@@ -0,0 +1,57 @@
+#ifndef MAGNETICSENSORPWM_LIB_H
+#define MAGNETICSENSORPWM_LIB_H
+
+#include "Arduino.h"
+#include "../common/base_classes/Sensor.h"
+#include "../common/foc_utils.h"
+#include "../common/time_utils.h"
+
+// This sensor has been tested with AS5048a running in PWM mode.
+
+class MagneticSensorPWM: public Sensor{
+ public:
+  /**
+    * MagneticSensorPWM class constructor
+    * @param _pinPWM the pin to read the PWM sensor input signal
+    */
+    MagneticSensorPWM(uint8_t _pinPWM,int _min = 0, int _max = 0);
+
+
+    // initialize the sensor hardware
+    void init();
+
+    int pinPWM;
+
+    // get current angle (rad)
+    float getAngle() override;
+    // get current angular velocity (rad/s)
+    float getVelocity() override;
+ 
+
+  private:
+    // raw count (typically in range of 0-1023)
+    int raw_count;
+    int min_raw_count;
+    int max_raw_count;
+    int cpr;
+    int read();
+
+    /**
+     * Function getting current angle register value
+     * it uses angle_register variable
+     */
+    int getRawCount();
+
+    // total angle tracking variables
+    float full_rotation_offset; //!<number of full rotations made
+    int raw_count_prev; //!< angle in previous position calculation step
+
+    // velocity calculation variables
+    float angle_prev; //!< angle in previous velocity calculation step
+    long velocity_calc_timestamp; //!< last velocity calculation timestamp
+    float velocity;
+    
+
+};
+
+#endif