Since the doc link on the extension at http://extensiondirectory.com/tools/arduino-extension.html asks for the phone to be set for USB media Transfer Protocol, and because the source code has references to file operations, there is a possibility that the data transfer is meant to work one file at a time. Since there are no mentions of file names in the blocks, the simplest case I can think of would be an instream text file. Since text files typically are terminated with hex zero in C, maybe it would be helpful to have some way of adding one to the end of a data stream. Here are some blocks (draggable) to generate a x'00' character...
