v1.0.1 to add PWM_StepperControl example

### Releases v1.0.1

1. Add example [PWM_StepperControl](https://github.com/khoih-prog/STM32_PWM/tree/main/examples/PWM_StepperControl) to demo how to control Stepper Motor using PWM

examples/PWM_StepperControl/PWM_StepperControl.ino

@@ -0,0 +1,214 @@
+/****************************************************************************************************************************
+  PWM_StepperControl.ino
+  
+  For STM32F/L/H/G/WB/MP1 boards
+  Written by Khoi Hoang
+
+  Built by Khoi Hoang https://github.com/khoih-prog/STM32_PWM
+  Licensed under MIT license
+
+  Hardware-based multi-channel PWM wrapper library for STM32F/L/H/G/WB/MP1 boards
+  
+  Credits of Paul van Dinther (https://github.com/dinther). Check https://github.com/khoih-prog/RP2040_PWM/issues/16
+*****************************************************************************************************************************/
+
+// Use with Stepper-Motor driver, such as TMC2209
+
+#if !( defined(STM32F0) || defined(STM32F1) || defined(STM32F2) || defined(STM32F3)  ||defined(STM32F4) || defined(STM32F7) || \
+       defined(STM32L0) || defined(STM32L1) || defined(STM32L4) || defined(STM32H7)  ||defined(STM32G0) || defined(STM32G4) || \
+       defined(STM32WB) || defined(STM32MP1) || defined(STM32L5))
+  #error This code is designed to run on STM32F/L/H/G/WB/MP1 platform! Please check your Tools->Board setting.
+#endif
+
+// These define's must be placed at the beginning before #include "ESP32_PWM.h"
+// _PWM_LOGLEVEL_ from 0 to 4
+// Don't define _PWM_LOGLEVEL_ > 0. Only for special ISR debugging only. Can hang the system.
+#define _PWM_LOGLEVEL_      4
+
+#define USING_MICROS_RESOLUTION       true    //false 
+
+#include "STM32_PWM.h"
+
+/////////////////////////////////////////////////
+
+// Change the pin according to your STM32 board. There is no single definition for all boards.
+#define pin0    PA0
+#define pin1    D1
+#define pin2    D2
+#define pin3    D3
+#define pin4    D4
+#define pin5    D5
+#define pin6    D6
+#define pin7    D7
+
+#define pin8    D8
+#define pin9    D9
+#define pin10   D10
+#define pin11   D11
+#define pin12   D12
+#define pin13   D13
+#define pin14   D14
+#define pin15   D15
+#define pin16   D16
+
+//////////////////////////////////////////////////////
+
+// Change the pin according to your STM32 board. There is no single definition for all boards.
+
+#if ( defined(STM32F1) && ( defined(ARDUINO_BLUEPILL_F103CB) || defined(ARDUINO_BLUEPILL_F103C8) ) )
+
+  #warning Using BLUEPILL_F103CB / BLUEPILL_F103C8 pins
+
+  // For F103CB => pin0, pin4, pin10 ============>> TimerIndex = 1, 2, 0
+  #define STEP_PIN        pin3
+
+#elif ( defined(STM32F7) && defined(ARDUINO_NUCLEO_F767ZI) )
+
+  #warning Using NUCLEO_F767ZI pins
+
+  // For F767ZI => pin0, pin3, pin9/10 ============>> TimerIndex = 1, 0, 3
+  #define STEP_PIN        pin3
+
+#elif ( defined(STM32L5) && defined(ARDUINO_NUCLEO_L552ZE_Q) )
+
+  #warning Using NUCLEO_L552ZE_Q pins
+
+  // For NUCLEO_L552ZE_Q => pin0, pin3, pin9/10 ============>> TimerIndex = 1, 0, 3
+  #define STEP_PIN        pin3
+
+#elif ( defined(STM32H7) && defined(ARDUINO_NUCLEO_H743ZI2) )
+
+  #warning Using NUCLEO_H743ZI2 pins
+
+  // For NUCLEO_L552ZE_Q => pin0, pin3, pin9/10 ============>> TimerIndex = 1, 0, 3
+  #define STEP_PIN        pin3
+
+#else
+
+  // For ??? => pin0, pin3, pin9/10 ============>> TimerIndex = 1, 0, 3
+  #define STEP_PIN        pin3
+
+#endif
+
+//////////////////////////////////////////////////////
+
+#define DIR_PIN         pin1
+
+TIM_TypeDef *stepperTimer;
+
+HardwareTimer *stepper;
+
+uint32_t channel;
+
+int previousSpeed = 0;
+
+// The Stepper RPM will be ( speed * 60 ) / steps-per-rev
+// For example, 28BYJ-48 Stepper Motor (https://lastminuteengineers.com/28byj48-stepper-motor-arduino-tutorial/) has 32 Steps/Rev
+// Speed = 640 Hz => Stepper RPM = (640 * 60 / 32) = 1200 RPM
+void setSpeed(int speed)
+{
+  // Do nothing if same speed
+  if (speed == previousSpeed)
+    return;
+
+  Serial.print(F("setSpeed = "));
+  Serial.println(speed);
+
+  // Create new instance for new speed  
+  if (stepper)
+    delete stepper;
+
+  stepper = new HardwareTimer(stepperTimer);
+
+  if (speed == 0)
+  {
+    // Use DC = 0 to stop stepper
+    stepper->setPWM(channel, STEP_PIN, 500, 0, nullptr);
+  }
+  else
+  {
+    //  Set the frequency of the PWM output and a duty cycle of 50%
+    digitalWrite(DIR_PIN, (speed < 0));
+    stepper->setPWM(channel, STEP_PIN, abs(speed), 50, nullptr);
+  }
+
+  previousSpeed = speed;
+}
+
+void initPWM(uint32_t step_pin)
+{
+  // Using pin = PA0, PA1, etc.
+  PinName pinNameToUse = digitalPinToPinName(step_pin);
+
+  // Automatically retrieve TIM instance and channel associated to pin
+  // This is used to be compatible with all STM32 series automatically.
+  stepperTimer = (TIM_TypeDef *) pinmap_peripheral(pinNameToUse, PinMap_PWM);
+
+  if (stepperTimer != nullptr)
+  {
+    uint8_t timerIndex = get_timer_index(stepperTimer);
+
+    // pin => 0, 1, etc
+    channel = STM_PIN_CHANNEL(pinmap_function( pinNameToUse, PinMap_PWM));
+
+    Serial.print("stepperTimer = 0x");
+    Serial.print( (uint32_t) stepperTimer, HEX);
+    Serial.print(", channel = ");
+    Serial.print(channel);
+    Serial.print(", TimerIndex = ");
+    Serial.print(get_timer_index(stepperTimer));
+    Serial.print(", PinName = ");
+    Serial.println( pinNameToUse );
+
+    stepper = new HardwareTimer(stepperTimer);
+
+    // SetPWM object and passed just a random frequency of 500 steps/s
+    // The Stepper RPM will be ( speed * 60 ) / steps-per-revolution
+    // The duty cycle is how you turn the motor on and off
+    previousSpeed = 500;
+    stepper->setPWM(channel, step_pin, previousSpeed, 0, nullptr);
+  }
+  else
+  {
+    Serial.println("ERROR => Wrong pin, You have to select another one. Skip NULL stepperTimer");
+  }  
+}
+
+void setup() 
+{
+  pinMode(STEP_PIN, OUTPUT);
+  digitalWrite(STEP_PIN, LOW);
+  pinMode(DIR_PIN, OUTPUT);
+  digitalWrite(DIR_PIN, LOW);
+
+  Serial.begin(115200);
+
+  while (!Serial && millis() < 5000);
+
+  delay(100);
+
+  Serial.print(F("\nStarting PWM_StepperControl on "));
+  Serial.println(BOARD_NAME);
+  Serial.println(STM32_PWM_VERSION);
+
+  initPWM(STEP_PIN);
+}
+
+void loop() 
+{
+  // The Stepper RPM will be ( speed * 60 ) / steps-per-rev
+  setSpeed(2000);
+  delay(3000);
+
+  // Stop before reversing
+  setSpeed(0);
+  delay(3000);
+
+  // Reversing
+  setSpeed(-1000);
+  delay(3000);
+
+  // Stop before reversing
+  setSpeed(0);
+  delay(3000);
+}