added a STM32MagneticSensorPWM

Author: Richard Unger

src/encoders/stm32pwmsensor/README.md

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+
+# STM32MagneticSensorPWM
+
+STM32 MCU specific PWM sensor class. This class uses the STM32's hardware timers to precisely capture the PWM input signal, and doesn't use interrupts or have MCU overhead.
+
+:warning: this code is not yet well tested.
+
+## Setup
+
+Please use an advanced control or general purpose timer pin on your STM32. Connect the sensor's PWM output to the MCU's input pin. Usually, pull-ups or pull-downs are not needed, but check your sensor's datasheet.
+
+:warning: only tested on 16 bit timers. Code changes may be needed to make it work on 32 but timers. Avoid using TIM2 and TIM5 unless you want to test it.
+
+The sensor needs the values `min_ticks` and `max-ticks` to be configured correctly to convert the PWM input into an angle. These values will depend on the sensor, but also on the MCU's timer clock speed.
+
+To print the current tick value, use:
+
+```
+sensor.getDutyCycleTicks();
+```
+
+By rotating the motor through several full turns while printing the ticks to the screen you will be able to determine the correct values empirically.
+
+## Usage
+
+```
+STM32MagneticSensorPWM sensor = STM32MagneticSensorPWM(PB7, 412, 6917); // sample values, yours will be different
+
+void setup() {
+    ...
+    sensor.init();
+    ...
+}
+```
+
+To use alternate function timers, set the PinName directly:
+
+```
+sensor._pin = PB_7_ALT1;  // manually set a PinName to use alternate timer function
+```
+
+PWM sensor may have a slow update time (not more often than once per PWM-period, e.g. at the PWM frequency):
+
+```
+sensor.min_elapsed_time = 0.001; // 1ms minimum sample time for velocity
+```

src/encoders/stm32pwmsensor/STM32MagneticSensorPWM.cpp

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+
+#include "./STM32MagneticSensorPWM.h"
+
+#if defined(_STM32_DEF_)
+
+#include "common/foc_utils.h"
+
+
+STM32MagneticSensorPWM::STM32MagneticSensorPWM(int pin, uint32_t _min_ticks, uint32_t _max_ticks) : STM32PWMInput(pin), max_ticks(_max_ticks), min_ticks(_min_ticks) {
+
+};
+
+
+
+STM32MagneticSensorPWM::~STM32MagneticSensorPWM(){};
+
+
+
+void STM32MagneticSensorPWM::init(){
+    initialized = (STM32PWMInput::initialize()==0);
+    if(initialized)
+        Sensor::init();
+};
+
+
+
+float STM32MagneticSensorPWM::getSensorAngle(){
+    uint32_t ticks = getDutyCycleTicks();
+    return (ticks - min_ticks) * _2PI / (max_ticks - min_ticks);
+};
+
+
+
+
+#endif

src/encoders/stm32pwmsensor/STM32MagneticSensorPWM.h

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+
+#pragma once
+
+
+#include <Arduino.h>
+
+
+#if defined(_STM32_DEF_)
+
+#include "common/base_classes/Sensor.h"
+#include "utilities/stm32pwm/STM32PWMInput.h"
+
+
+class STM32MagneticSensorPWM : public Sensor, public STM32PWMInput {
+    public:
+        STM32MagneticSensorPWM(int pin, uint32_t _min_ticks = 0, uint32_t _max_ticks = 0x0FFF);
+        ~STM32MagneticSensorPWM();
+
+        void init() override;
+
+        uint32_t max_ticks = 0x0FFF;
+        uint32_t min_ticks = 0;
+        bool initialized = false;
+    protected:
+        float getSensorAngle() override;
+};
+
+#endif