I think the authors tack on this was faster than decompiling the binary. Many things are pretty straightforward mucking about in binaries, but I'd bet that USB

I think the authors tack on this was faster than decompiling the binary. Many things are pretty straightforward mucking about in binaries, but I'd bet that USB transactions are not one of them. Combine that with this being an easy-to-sniff over-the-wire protocol, protocol analysis is how I would have done it too. On the other hand, I thought tessel was an open source project? Why not just hack together your own DFU loader? It basically just needs to read data over USB from the PC, and write it to nonvolatile/flash.