yeah, those chips have definitely piqued my interest too - the ability to do on-the-fly FFT/IFFTs pretty much means that the sky is the limit. Well, the sky and ones ability to work with 0.4 mm pitches.
Fine pitch is pretty easy once you use solder masks. apply flux. melt an entire row of fine solder with one swipe. suck up the excess with wick. inspect with $10 eye magnifier thing.
Harder is designing the PCB layout. old rules don't apply as much, and there are new rules when you deal with high speed micros. double sided board is absolutelly necissary since you need a ground plane, and you need to keep under the chip as free from traces as you can to allow inductance wizardry to happen, or something. also, lots and lots of vias and decoupling caps.
There exist PIC32's in DIP which operate at half frequency, mightr be an option if you want to skip the layout trickiness.
http://nearworlds.org/stuff/pic32_caps_v3.jpglike here's a layout I had done (the PIC32 is on the other side of roughly the center) which didn't work well. the pic was unstable and glitchy because I later learned that the ground plane was all cut up and cluttered right under the chip. so I moved stuff away from the chip to give it breathing room, and used a lot of vias to keep traces under it to a minimum, and to make the ground plane "one piece".
http://nearworlds.org/stuff/pic32_caps_v4.jpgOtherwise yeah, they're pretty cool. It's not a dedicated DSP though, so even a "slower" real DSP like the FV-1 might perform better for some things. but the pic hdoes have DSP features and does them alright. and for raw general horsepower they're pretty nice too! I'm sampling audio at 96khz and performing a whole bunch of multiplication and division on 32bit integers per-sample and it isn't even breaking a sweat. most of the sample time I'm wasting is the slow clock of the external ADC I'm using, but that's hardly the micro's fault.
