The title says it all. Can I use an USB Mass Storage Device insted of the MicroSD Card? And anyone knows which path will it use?
I wrote UsbFat. It has the same basic API as SdFat and most of the SD.h calls.
You need a USB Host Shield or an Arduino ADK.
Another USB host shield:
Give a look into MAX3421E, it is a USB host control chip that has been used with Arduino to add Host capability.
http://www.digikey.com/product-search/en?pv16=11423&FV=fff40027%2Cfff80319&k=max3421e&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25
Give a look into MAX3421E,
The Circuits@Home shield uses a MAX3421E. They also have a small breakout board.
The Arduino ADK has a MAX3421E.
You can find cheap MAX3421E boards on ebay.
Hi fat16lib,
im searching for a easy example to write a txt file on my USB stick. For this im using a Adruino Mega 2560 and the USB Host Shield. I also tried to use the example from circuits@home but it wont work correctly... I just see if a stick is plugged in or not. And yesterday evening i found your post here with your library. I think this is exactly what i need. But I cant include it 
I get everytime the following error:
Specified folder/zip file does not contain a valid library
I use the Arduino IDE 1.6.5
Could you help me?
Unzip the file and read the Installation section of the html documentation.
Thank you sooooooo much. It works 