updated pwm example

Author: Heltec-Aaron-Lee

libraries/Basics/examples/PWM/PWM.ino

@@ -3,15 +3,32 @@
 
 void setup() {
   // put your setup code here, to run once:
-	pinMode(PWM1,OUTPUT);
-	pinMode(PWM2,OUTPUT);
+
+  /*PWM CLK frequency default is 12M;
+   *PWM CLK frequency value:
+   *PWM_CLK_FREQ_48M
+   *PWM_CLK_FREQ_24M
+   *PWM_CLK_FREQ_16M
+   *PWM_CLK_FREQ_12M
+   *PWM_CLK_FREQ_8M
+   *PWM_CLK_FREQ_6M
+   *PWM_CLK_FREQ_4M
+   *PWM_CLK_FREQ_3M
+   *PWM_CLK_FREQ_2M
+   *PWM_CLK_FREQ_1M
+   */
+  setPWM_Frequency(PWM_CLK_FREQ_12M);
+
+  //pwm period can be 0xFF~0xFFFF, default is 0xFFFF
+  setPWM_ComparePeriod(0xFFFF);
+  pinMode(PWM1,OUTPUT);
+  pinMode(PWM2,OUTPUT);
 }
 
 uint16_t a=0;
 uint16_t b=0;
 
 void loop() {
-  // PWM frequency is 65535
   analogWrite(PWM1,a);
   analogWrite(PWM2,b);
   delay(10);