il DHT-U non ce l'ho... ma se leggi su:
2, Beta test version for DHT-U new firmware with data log function.
2.1, SD card logo will show up on the main screen after it is inserted into SD reader;
2.2, Press the top left button on DHT-U to enter setting menu for data log;
2.3, Log time (time to start data log: 1/3/5 minutes after powering up) and log step (time interval: 1/2/5 seconds) are selectable;
2.4, File format for data log: txt.
ps: c'è uno slot per memory card? Magari ce la devi mettere
