add setVelocity method and explanation for ESP32 support

README.md

@@ -1,3 +1,16 @@
+# Explanation
+
+The library is forked from [L298n](https://github.com/AndreaLombardo/L298N).
+The original library is designed for Arduino board, using `analogWrite`, which may cause some problem on ESP32.
+Using [ESP32_AnalogWrite](https://github.com/erropix/ESP32_AnalogWrite) or [AnalogWrite_ESP32](https://github.com/pablomarquez76/AnalogWrite_ESP32) can overwrite `ledcWrite` of ESP32 to `analogWrite`.
+As [pablomarquez76](https://github.com/pablomarquez76/AnalogWrite_ESP32/issues/6) saind, ESP32 has supported `analogWrite` after 2.0.11. The official document is [at here](https://docs.espressif.com/projects/arduino-esp32/en/latest/api/ledc.html?highlight=analogWrite#analogwrite).The resolution is form 0 to 255, testing normal. So nothing needs change.
+
+I added a method to get input from -255 to 255 to control the motor. It is for easier direction control.
+
+I tested it with PID library. Sometimes PID always output 0. Sometimes it works. I didn't find the reason. It might because ESP32Encoder or this repo use the same timer with PID. I am not sure. Be careful.
+
+The below is original readme.
+
 # L298N Library
 
 An easy to use L298N library to control DC Motors with Arduino.

src/L298N.cpp

@@ -143,6 +143,44 @@ void L298N::reset() {
   _canMove = true;
 }
 
+// the velocity is a number between -255 and 255
+// positive values are for forward movements
+// negative values are for backward movements
+void L298N::setVelocity(int velocity){
+  if (velocity > 255) {
+    velocity = 255;
+  } else if (velocity < -255) {
+    velocity = -255;
+  }
+
+  if (velocity > 0) {
+    this->setSpeed((unsigned short)velocity);
+    this->forward();
+  } else if (velocity < 0) {
+    this->setSpeed((unsigned short)(-velocity));
+    this->backward();
+  } else {
+    this->stop();
+  }
+}
+
+// the acceleration can be positive or negative
+// negative values does not mean deceleration
+// it means the direction of the acceleration is negative
+void L298N::accelerate(int acceleration) {
+  int velocity = this->getSpeed();
+  if (_direction == BACKWARD) {
+    velocity = -velocity;
+  }
+  velocity += acceleration;
+  if (velocity > 255) {
+    velocity = 255;
+  } else if (velocity < -255) {
+    velocity = -255;
+  }
+  this->setVelocity(velocity);
+}
+
 boolean L298N::isMoving() {
   return _isMoving;
 }

src/L298N.h

@@ -30,6 +30,8 @@ class L298N
    void runFor(unsigned long delay, L298N::Direction direction, CallBackFunction callback);
    void stop();
    void reset();
+   void setVelocity(int velocity);
+   void accelerate(int acceleration);
    boolean isMoving();
    Direction getDirection();