v1.7.0 to add new PushPull mode

### Releases v1.7.0

1. Add functions `setPWMPushPull_Int`, `setPWMPushPull` and `setPWMPushPull_Period` for the new `PushPull` mode. Check [pwm_set_output_polarity #21](#21)
2. Add these examples to demo the new `PushPull` mode
  - [PWM_PushPull](https://github.com/khoih-prog/RP2040_PWM/tree/main/examples/PWM_PushPull)
  - [PWM_PushPull_DynamicDC](https://github.com/khoih-prog/RP2040_PWM/tree/main/examples/PWM_PushPull_DynamicDC)
  - [PWM_PushPull_DynamicFreq](https://github.com/khoih-prog/RP2040_PWM/tree/main/examples/PWM_PushPull_DynamicFreq)
3. Fix bug of half frequency when using `phaseCorrect` mode
4. Improve `README.md` so that links can be used in other sites, such as `PIO`

Author: khoih-prog

examples/PWM_PushPull/PWM_PushPull.ino

@@ -0,0 +1,69 @@
+/****************************************************************************************************************************
+  PWM_PushPull.ino
+  For RP2040 boards
+  Written by Khoi Hoang
+
+  Built by Khoi Hoang https://github.com/khoih-prog/RP2040_PWM
+  Licensed under MIT license
+
+  The RP2040 PWM block has 8 identical slices. Each slice can drive two PWM output signals, or measure the frequency
+  or duty cycle of an input signal. This gives a total of up to 16 controllable PWM outputs. All 30 GPIO pins can be driven
+  by the PWM block
+*****************************************************************************************************************************/
+
+#define _PWM_LOGLEVEL_        4
+#include "RP2040_PWM.h"
+
+//creates pwm instance
+RP2040_PWM* PWM_Instance;
+
+float frequency = 2000.0f;
+float dutyCycle = 30.0f;
+
+// Pins have to be in pairs of the same PWM slice / channel
+// Check https://github.com/khoih-prog/RP2040_PWM#programmers-model
+// For example: pins 0/1, 2/3, 4/5, 6/7, 8/9, 10/11, 12/13, 14/15, 16/17, 18/19, 20/21, 22/23, 24/25, 26/27, 28/29
+
+#define pinToUseA      18     // PWM1A
+#define pinToUseB      19     // PWM1A
+
+void printPWMInfo(RP2040_PWM* PWM_Instance)
+{
+  uint32_t div = PWM_Instance->get_DIV();
+  uint32_t top = PWM_Instance->get_TOP();
+
+  Serial.print("Actual PWM Frequency = ");
+  Serial.println(PWM_Instance->getActualFreq());
+
+  PWM_LOGDEBUG5("TOP =", top, ", DIV =", div, ", CPU_freq =", PWM_Instance->get_freq_CPU());
+}
+
+void setup()
+{ 
+  Serial.begin(115200);
+
+  while (!Serial && millis() < 5000);
+
+  delay(100);
+
+  Serial.print(F("\nStarting PWM_PushPull on "));
+  Serial.println(BOARD_NAME);
+  Serial.println(RP2040_PWM_VERSION);
+
+  // Use just one of these 2 for a pair
+  // assigns pinToUseA, with frequency of 200 Hz and a duty cycle of 0%
+  PWM_Instance = new RP2040_PWM(pinToUseA, frequency, 0);
+  // assigns pinToUseB, with frequency of 200 Hz and a duty cycle of 0%
+  //PWM_Instance = new RP2040_PWM(pinToUseB, frequency, 0);
+
+  // pinToUseA always with same polarity, pinToUseB with reversed polarity
+  //PWM_Instance->setPWMPushPull(pinToUseA, pinToUseB, frequency, dutyCycle);
+  // pinToUseA always with same polarity, pinToUseB shifted 180 deg
+  PWM_Instance->setPWMPushPull(pinToUseA, pinToUseB, frequency, dutyCycle);
+
+  printPWMInfo(PWM_Instance);
+}
+
+void loop()
+{
+}

examples/PWM_PushPull_DynamicDC/PWM_PushPull_DynamicDC.ino

@@ -0,0 +1,82 @@
+/****************************************************************************************************************************
+  PWM_PushPull_DynamicDC.ino
+  For RP2040 boards
+  Written by Khoi Hoang
+
+  Built by Khoi Hoang https://github.com/khoih-prog/RP2040_PWM
+  Licensed under MIT license
+
+  The RP2040 PWM block has 8 identical slices. Each slice can drive two PWM output signals, or measure the frequency
+  or duty cycle of an input signal. This gives a total of up to 16 controllable PWM outputs. All 30 GPIO pins can be driven
+  by the PWM block
+*****************************************************************************************************************************/
+
+#define _PWM_LOGLEVEL_        4
+#include "RP2040_PWM.h"
+
+//creates pwm instance
+RP2040_PWM* PWM_Instance;
+
+float frequency = 2000.0f;
+float dutyCycle;
+
+// Pins have to be in pairs of the same PWM slice / channel
+// Check https://github.com/khoih-prog/RP2040_PWM#programmers-model
+// For example: pins 0/1, 2/3, 4/5, 6/7, 8/9, 10/11, 12/13, 14/15, 16/17, 18/19, 20/21, 22/23, 24/25, 26/27, 28/29
+
+#define pinToUseA      18     // PWM1A
+#define pinToUseB      19     // PWM1A
+
+void printPWMInfo(RP2040_PWM* PWM_Instance)
+{
+  uint32_t div = PWM_Instance->get_DIV();
+  uint32_t top = PWM_Instance->get_TOP();
+
+  Serial.print("Actual PWM Frequency = ");
+  Serial.println(PWM_Instance->getActualFreq());
+
+  PWM_LOGDEBUG5("TOP =", top, ", DIV =", div, ", CPU_freq =", PWM_Instance->get_freq_CPU());
+}
+
+void setup()
+{
+  Serial.begin(115200);
+
+  while (!Serial && millis() < 5000);
+
+  delay(100);
+
+  Serial.print(F("\nStarting PWM_PushPull_DynamicDC on "));
+  Serial.println(BOARD_NAME);
+  Serial.println(RP2040_PWM_VERSION);
+
+  // Use just one of these 2 for a pair
+  // assigns pinToUseA, with frequency of 200 Hz and a duty cycle of 0%
+  PWM_Instance = new RP2040_PWM(pinToUseA, frequency, 0);
+  // assigns pinToUseB, with frequency of 200 Hz and a duty cycle of 0%
+  //PWM_Instance = new RP2040_PWM(pinToUseB, frequency, 0);
+
+  PWM_Instance->setPWMPushPull(pinToUseA, pinToUseB, frequency, 0);
+}
+
+void loop()
+{ 
+  dutyCycle = 50.0f;
+
+  Serial.print(F("Change PWM DutyCycle to "));
+  Serial.println(dutyCycle);
+  PWM_Instance->setPWMPushPull(pinToUseA, pinToUseB, frequency, dutyCycle);
+
+  printPWMInfo(PWM_Instance);
+
+  delay(10000);
+  
+  dutyCycle = 10.0f;
+
+  Serial.print(F("Change PWM DutyCycle to "));
+  Serial.println(dutyCycle);
+  PWM_Instance->setPWMPushPull(pinToUseA, pinToUseB, frequency, dutyCycle);
+  printPWMInfo(PWM_Instance);
+
+  delay(5000);
+}

examples/PWM_PushPull_DynamicFreq/PWM_PushPull_DynamicFreq.ino

@@ -0,0 +1,81 @@
+/****************************************************************************************************************************
+  PWM_PushPull_DynamicFreq.ino
+  For RP2040 boards
+  Written by Khoi Hoang
+
+  Built by Khoi Hoang https://github.com/khoih-prog/RP2040_PWM
+  Licensed under MIT license
+
+  The RP2040 PWM block has 8 identical slices. Each slice can drive two PWM output signals, or measure the frequency
+  or duty cycle of an input signal. This gives a total of up to 16 controllable PWM outputs. All 30 GPIO pins can be driven
+  by the PWM block
+*****************************************************************************************************************************/
+
+#define _PWM_LOGLEVEL_        4
+#include "RP2040_PWM.h"
+
+//creates pwm instance
+RP2040_PWM* PWM_Instance;
+
+float frequency = 2000.0f;
+float dutyCycle = 30.0f;
+
+// Pins have to be in pairs of the same PWM slice / channel
+// Check https://github.com/khoih-prog/RP2040_PWM#programmers-model
+// For example: pins 0/1, 2/3, 4/5, 6/7, 8/9, 10/11, 12/13, 14/15, 16/17, 18/19, 20/21, 22/23, 24/25, 26/27, 28/29
+
+#define pinToUseA      18     // PWM1A
+#define pinToUseB      19     // PWM1A
+
+void printPWMInfo(RP2040_PWM* PWM_Instance)
+{
+  uint32_t div = PWM_Instance->get_DIV();
+  uint32_t top = PWM_Instance->get_TOP();
+
+  Serial.print("Actual PWM Frequency = ");
+  Serial.println(PWM_Instance->getActualFreq());
+
+  PWM_LOGDEBUG5("TOP =", top, ", DIV =", div, ", CPU_freq =", PWM_Instance->get_freq_CPU());
+}
+
+void setup()
+{ 
+  Serial.begin(115200);
+
+  while (!Serial && millis() < 5000);
+
+  delay(100);
+
+  Serial.print(F("\nStarting PWM_PushPull_DynamicFreq on "));
+  Serial.println(BOARD_NAME);
+  Serial.println(RP2040_PWM_VERSION);
+
+  // Use just one of these 2 for a pair
+  // assigns pinToUseA, with frequency of 200 Hz and a duty cycle of 0%
+  PWM_Instance = new RP2040_PWM(pinToUseA, frequency, 0);
+  // assigns pinToUseB, with frequency of 200 Hz and a duty cycle of 0%
+  //PWM_Instance = new RP2040_PWM(pinToUseB, frequency, 0);
+
+  PWM_Instance->setPWMPushPull(pinToUseA, pinToUseB, frequency, 0);
+}
+
+void loop()
+{
+  frequency = 2000.0f;
+
+  Serial.print(F("Change PWM Freq to "));
+  Serial.println(frequency);
+  PWM_Instance->setPWMPushPull(pinToUseA, pinToUseB, frequency, dutyCycle);
+  printPWMInfo(PWM_Instance);
+
+  delay(5000);
+
+  frequency = 1000.0f;
+
+  Serial.print(F("Change PWM Freq to "));
+  Serial.println(frequency);
+  PWM_Instance->setPWMPushPull(pinToUseA, pinToUseB, frequency, dutyCycle);
+  printPWMInfo(PWM_Instance);
+
+  delay(5000);
+}