#define PWM_CT2_A  11 //OC2A
#define PWM_CT2_B   3 //OC2B

// LGT8F328P has 12 bits.

#define maxpwm 255

void ct2_init()
{
  pinMode(PWM_CT2_A,OUTPUT);
  pinMode(PWM_CT2_B,OUTPUT);

  TCCR2A = (1 << COM2B1)|(1 << COM2A1)|(1 << WGM21)|(1 << WGM20);  //fast PWM INV
  TCCR2B = (1 << CS20);       // prescaler 0
  OCR2A = 5;                          // pwm value  
  OCR2B = 5;                          // pwm value  
}

void setup() 
{
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(115200);
  ct2_init();
}

uint8_t pwm = 8;
char in_ch;

void loop() 
{ 
  //OCR2B = (int)pwm;
  if (Serial.available())
  {
    in_ch = Serial.read();
    if (in_ch == '1') pwm = constrain(pwm+8,0,250);
    if (in_ch == '2') pwm = constrain(pwm-8,0,250);
    OCR2A = pwm;
    OCR2B = pwm;
  }
  delay(500);
}