The TinyShield USB & ICP add USB support for the TinyDuino via a micro-USB connector and uses the very popular FTDI USB to Serial converter IC (as used on most standard Arduino models). Using this board allows you to download new sketches via the Arduino IDE to your TinyDuino, and also allows you to add USB communication capabilities to your projects. This board supports RX and TX status LEDs so you can visualize the serial traffic to and from your TinyDuino.
This board also uses the DTR line from the FTDI IC to support the auto-reset function when a new sketch is downloaded to the processor – eliminating the need for you to hit the reset button to reprogram your TinyDuino.
A In-Circuit programming (ICP) 6-pin connection is also available on this board (the header is not included by default), which can be used to program the Atmel microcontroller on the TinyDuino using an external programmer. The size and pinout of this connector is the new Atmel standard, and this can be used directly with newer external programmers like the Atmel JTAGICE 3.