Golang and Arduino

unsigned long unixtime;

void setup() {
  Serial.begin(9600);
}

unsigned long timeNow;

void loop() {
  if(millis() - timeNow >= 1000) { // every second increment unixtime
    timeNow = millis();
    unixtime += 1;
    sprint();
  }
}

void sprint() {
  int s = unixtime % 60;
  int m = (unixtime % 3600) / 60;
  int h = (unixtime % 86400) / 3600; 

  char buff[64];
  snprintf(buff, 64, "%02d %02d %02d", h, m, s);
  Serial.println(buff);
}