magnetic pwm sensors initial implementation

Author: askuric

examples/utils/sensor_test/magnetic_sensors/magnetic_sensor_pwm_example/find_raw_min_max/find_raw_min_max.ino

@@ -0,0 +1,30 @@
+#include <SimpleFOC.h>
+
+
+/**
+ * An example to find out the raw max and min count to be provided to the constructor
+ * SPin your motor/sensor/magnet to see what is the maximum output of the sensor and what is the minimum value 
+ * And replace values 4 and 904 with new values. Once when you replace them make sure there is no jump in the angle reading sensor.getAngle(). 
+ * If there is a jump that means you can still find better values. 
+ */
+MagneticSensorPWM sensor = MagneticSensorPWM(2, 4, 904);
+void doPWM(){sensor.handlePWM();}
+
+void setup() {
+  // monitoring port
+  Serial.begin(115200);
+
+  // initialise magnetic sensor hardware
+  sensor.init();
+  sensor.enableInterrupt(doPWM);
+
+  Serial.println("Sensor ready");
+  _delay(1000);
+}
+
+void loop() {
+  // display the angle and the angular velocity to the terminal
+  Serial.print(sensor.pulse_length_us);
+  Serial.print("\t");
+  Serial.println(sensor.getAngle());
+}

examples/utils/sensor_test/magnetic_sensors/magnetic_sensor_pwm_example/magnetic_sensor_pwm/magnetic_sensor_pwm.ino

@@ -0,0 +1,32 @@
+#include <SimpleFOC.h>
+
+
+/**
+ * Magnetic sensor reading pwm signal on pin 2.  The pwm duty cycle is proportional to the sensor angle.
+ * 
+ * MagneticSensorPWM(uint8_t MagneticSensorPWM, int _min, int _max)
+ * - pinPWM         - the pin that is reading the pwm from magnetic sensor
+ * - min_raw_count  - the smallest expected reading.  Whilst you might expect it to be 0 it is often ~5.  Getting this wrong results in a small click once per revolution
+ * - max_raw_count  - the largest value read.  whilst you might expect it to be 1kHz = 1000 it is often ~910. depending on the exact frequency and saturation
+ */
+MagneticSensorPWM sensor = MagneticSensorPWM(2, 4, 904);
+void doPWM(){sensor.handlePWM();}
+
+void setup() {
+  // monitoring port
+  Serial.begin(115200);
+
+  // initialise magnetic sensor hardware
+  sensor.init();
+  sensor.enableInterrupt(doPWM);
+
+  Serial.println("Sensor ready");
+  _delay(1000);
+}
+
+void loop() {
+  // display the angle and the angular velocity to the terminal
+  Serial.print(sensor.getAngle());
+  Serial.print("\t");
+  Serial.println(sensor.getVelocity());
+}

examples/utils/sensor_test/magnetic_sensors/magnetic_sensor_pwm_example/magnetic_sensor_pwm_software_interrupt/magnetic_sensor_pwm_software_interrupt.ino

@@ -0,0 +1,38 @@
+#include <SimpleFOC.h>
+
+// software interrupt library
+#include <PciManager.h>
+#include <PciListenerImp.h>
+
+/**
+ * Magnetic sensor reading analog voltage on pin which does not have hardware interrupt support. Such as A0.
+ * 
+ * MagneticSensorPWM(uint8_t MagneticSensorPWM, int _min, int _max)
+ * - pinPWM         - the pin that is reading the pwm from magnetic sensor
+ * - min_raw_count  - the smallest expected reading.  Whilst you might expect it to be 0 it is often ~5.  Getting this wrong results in a small click once per revolution
+ * - max_raw_count  - the largest value read.  whilst you might expect it to be 1kHz = 1000 it is often ~910. depending on the exact frequency and saturation
+ */
+MagneticSensorPWM sensor = MagneticSensorPWM(A0, 4, 904);
+void doPWM(){sensor.handlePWM();}
+
+// encoder interrupt init
+PciListenerImp listenerPWM(sensor.pinPWM, doPWM);}
+
+void setup() {
+  // monitoring port
+  Serial.begin(115200);
+
+  // initialise magnetic sensor hardware
+  sensor.init();
+  PciManager.registerListener(&listenerPWM);
+
+  Serial.println("Sensor ready");
+  _delay(1000);
+}
+
+void loop() {
+  // display the angle and the angular velocity to the terminal
+  Serial.print(sensor.getAngle());
+  Serial.print("\t");
+  Serial.println(sensor.getVelocity());
+}

keywords.txt

@@ -8,6 +8,7 @@ HallSensors	KEYWORD1
 MagneticSensorSPI	KEYWORD1
 MagneticSensorI2C	KEYWORD1
 MagneticSensorAnalog	KEYWORD1
+MagneticSensorPWM	KEYWORD1
 BLDCDriver3PWM	KEYWORD1    
 BLDCDriver6PWM	KEYWORD1    
 BLDCDriver	KEYWORD1    
@@ -92,6 +93,8 @@ scalar	KEYWORD2
 pid	KEYWORD2
 lpf	KEYWORD2
 motor	KEYWORD2
+handlePWM	KEYWORD2
+enableInterrupt	KEYWORD2
 
 
 

src/sensors/MagneticSensorPWM.cpp

@@ -1,4 +1,5 @@
 #include "MagneticSensorPWM.h"
+#include "Arduino.h"
 
 /** MagneticSensorPWM(uint8_t _pinPWM, int _min, int _max)
  * @param _pinPWM  the pin that is reading the pwm from magnetic sensor
@@ -14,6 +15,9 @@ MagneticSensorPWM::MagneticSensorPWM(uint8_t _pinPWM, int _min_raw_count, int _m
     max_raw_count = _max_raw_count;
 
     pinMode(pinPWM, INPUT);
+
+    // init last call 
+    last_call_us = _micros();
 }
 
 
@@ -57,10 +61,35 @@ float MagneticSensorPWM::getAngle(){
 
 //  get velocity (rad/s)
 float MagneticSensorPWM::getVelocity(){
-  return velocity;
+    return velocity;
 }
 
 // read the raw counter of the magnetic sensor
 int MagneticSensorPWM::getRawCount(){
-	return pulseIn(pinPWM,HIGH);
+#if defined(__AVR_ATmega328P__) || defined(__AVR_ATmega168__) || defined(__AVR_ATmega328PB__)  || defined(__AVR_ATmega2560__) // if mcu is not atmega328 && if mcu is not atmega2560
+    pulse_length_us = pulseIn(pinPWM, HIGH);
+#endif
+
+    return pulse_length_us;
+}
+
+
+void MagneticSensorPWM::handlePWM() {
+    //  unsigned long now_us = ticks();
+    unsigned long now_us = _micros();
+    
+    // if falling edge, calculate the pulse length
+    if (!digitalRead(pinPWM)) pulse_length_us = now_us - last_call_us;
+
+    // save the currrent timestamp for the next call
+    last_call_us = now_us;
 }
+
+// function enabling hardware interrupts of the for the callback provided
+// if callback is not provided then the interrupt is not enabled
+void MagneticSensorPWM::enableInterrupt(void (*doPWM)()){
+    #if !defined(__AVR_ATmega328P__) && !defined(__AVR_ATmega168__) && !defined(__AVR_ATmega328PB__)  && !defined(__AVR_ATmega2560__) // if mcu is not atmega328 && if mcu is not atmega2560
+        // enable interrupts on pwm input pin
+        attachInterrupt(digitalPinToInterrupt(pinPWM), doPWM, CHANGE);
+    #endif
+}

src/sensors/MagneticSensorPWM.h

@@ -26,7 +26,11 @@ class MagneticSensorPWM: public Sensor{
     float getAngle() override;
     // get current angular velocity (rad/s)
     float getVelocity() override;
- 
+  
+    // pwm handler
+    void handlePWM();
+    void enableInterrupt(void (*doPWM)());
+    unsigned long pulse_length_us;
 
   private:
     // raw count (typically in range of 0-1023)
@@ -50,6 +54,10 @@ class MagneticSensorPWM: public Sensor{
     float angle_prev; //!< angle in previous velocity calculation step
     long velocity_calc_timestamp; //!< last velocity calculation timestamp
     float velocity;
+
+    // time tracking variables
+    unsigned long last_call_us;
+    // unsigned long pulse_length_us;
 
 
 };