From the comments on our FTDI’s new X-Series of USB device chips post:
I’ve been using the FT221X. Regarding the leadless package, assembly by hand is doable with the right tools: a hot air rework station such as the Hakko 803B, and either a stencil or a droplet dispenser (or both) for applying the paste — applying paste with nothing more than a simple syringe is out of the question. For a one-off project, the evaluation module is only $20 and is all through-hole.
Regarding BSOD, I am using 32-bit Windows Vista, and I’ve yet to have an issue with the FT221X. Any time the serial port hangs, it’s some bug in my host PC application software, not the FT221X.
My only complaint is FTDI’s horrendous documentation and marketing. The FT221X is marketed as a USB to SPI interface, but it is not really SPI. It is FTDI’s own protocol, FT1248. It’s a good protocol: it allows for very fast communication — faster than SPI — but it is incompatible with the USI hardware module (the Atmel SPI module on their ATtiny microcontrollers).
You can still salvage some of the Atmel USI module, but you need to implement part of the SPI in software (defeats the point of doing SPI). A doable task, but annoying when you’re going into a project thinking that the FTDI chip is designed to do this already off-the-shelf.
Another complaint is with their configuration utility software. I hit upon two show-stopping bugs in their FT_Prog utility that held up my development time. On the up-side, they have been great about revising the software and releasing a revision within a few days of reporting the bug.
Another nice feature is the bit bang mode. For example, you can use the bit bang mode to roll your own SPI interface (and since you can do whatever you want in bit bang mode, this could be a master or a slave). There are three bit bang modes. Again, the documentation sucks, so you kind of just have to try out each mode for yourself to understand what is going on.
Public domain photo by DustyDingo.