#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);
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);
}