#define GPIO_pin 5
uint32_t Freq = 0;
void setup() {
  pinMode(GPIO_pin, OUTPUT);
  Serial.begin(115200);
  Freq=getCpuFrequencyMhz();
  Serial.print("Cpu Freq=");
  Serial.print(Freq);
  // put your setup code here, to run once:
  Serial.println("MHz");
  Freq=getXtalFrequencyMhz();
  Serial.print("Xtal Freq=");
  Serial.print(Freq);
  Serial.println("MHz");
  Freq=getApbFrequency();
  Serial.print("Apb Freq=");
  Serial.print(Freq);
  Serial.println("Hz");

}

void loop()
 {
  
  digitalWrite(GPIO_pin,1);
  digitalWrite(GPIO_pin,0);
}