Add PWM_StepperControl example

Credits of `Paul van Dinther` (https://github.com/dinther). Check khoih-prog/RP2040_PWM#16

examples/PWM_StepperControl/PWM_StepperControl.ino

@@ -0,0 +1,85 @@
+/****************************************************************************************************************************
+  PWM_StepperControl.ino
+  
+  For Teensy boards (Teensy 2.x, Teensy LC, Teensy 3.x, Teensy 4.x, etc.)
+  Written by Khoi Hoang
+
+  Built by Khoi Hoang https://github.com/khoih-prog/Teensy_PWM
+  Licensed under MIT license
+
+  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
+
+#define _PWM_LOGLEVEL_        4
+
+#include <Teensy_PWM.h>
+
+#define USING_FLEX_TIMERS      true
+
+#if USING_FLEX_TIMERS
+  #define STEP_PIN       5
+#else
+  #define STEP_PIN       15
+#endif
+
+#define DIR_PIN         9
+
+float frequency;
+float dutyCycle;
+
+Teensy_PWM* stepper;
+
+void setSpeed(int speed)
+{
+  if (speed == 0)
+  {
+    // Use DC = 0 to stop stepper
+    stepper->setPWM(STEP_PIN, 500, 0);
+  }
+  else
+  {
+    //  Set the frequency of the PWM output and a duty cycle of 50%
+    digitalWrite(DIR_PIN, (speed < 0));
+    stepper->setPWM(STEP_PIN, abs(speed), 50);
+  }
+}
+
+void setup() 
+{
+  pinMode(DIR_PIN, OUTPUT);
+
+  Serial.begin(115200);
+
+  while (!Serial && millis() < 5000);
+
+  delay(100);
+
+#if USING_FLEX_TIMERS
+  Serial.print(F("\nStarting PWM_StepperControl using FlexTimers on "));
+#else
+  Serial.print(F("\nStarting PWM_StepperControl using QuadTimers on "));
+#endif
+
+  Serial.println(BOARD_NAME);
+  Serial.println(TEENSY_PWM_VERSION);
+
+  //  Create PWM object and passed just a random frequency of 500 in it
+  //  The duty cycle is how you turn the motor on and off
+  stepper = new Teensy_PWM(STEP_PIN, 500, 0);
+}
+
+void loop() 
+{
+  setSpeed(1000);
+  delay(3000);
+
+  // Stop before reversing
+  setSpeed(0);
+  delay(3000);
+
+  // Reversing
+  setSpeed(-500);
+  delay(3000);
+}