 	<< endl;
 
   // Read a block from the flash; measure time
-  uint8_t buf[256];
+  uint8_t buf[512];
   static uint32_t src = 0L;
   uint32_t start = RTC::micros();
   int res = flash.read(buf, src, sizeof(buf));

  start = RTC::micros();
  res = flash.write(addr, buf, sizeof(buf));
  us = RTC::micros() - start;
  trace << PSTR("write: dest = ") << addr 
	<< PSTR(", bytes = ") << sizeof(buf)
	<< PSTR(", us = ") << us 
	<< PSTR(", Kbyte/s = ") << 1000.0 * sizeof(buf) / us
	<< endl;
  ASSERT(res == sizeof(buf));
  SLEEP(5);
}


  uint32_t us = RTC::micros() - start;
  ASSERT(flash.is_ready());
  ASSERT(res == sizeof(data));
  trace << PSTR("write: dest = ") << hex << addr 
	<< PSTR(", bytes = ") << sizeof(data)
	<< PSTR(", us = ") << us 
	<< PSTR(", Kbyte/s = ") << 1000.0 * sizeof(data) / us
