   trace.begin(&uart, PSTR("CosaFAT16: started"));
   TRACE(free_memory());
   TRACE(sizeof(FAT16::File));
+  TRACE(CLOCK);
   ASSERT(sd.begin(CLOCK));
   ASSERT(FAT16::begin(&sd));
 }

void loop()
{
  static const size_t BUF_MAX = 512;
  static const uint8_t K_BYTE = 100;
  uint8_t buf[BUF_MAX];
  uint32_t start, stop;
  FAT16::File file;

  ASSERT(file.is_open());
  char msg[] = "Nisse badar.\n";
  size = strlen(msg);
  ASSERT(file.write(msg, strlen(msg)) == (int) size);
  ASSERT(file.close());
  stop = RTC::millis();
  trace << PSTR("Open/Write/Close file:");
