Is there stable support for this architecture in GCC and related projects? That is, is there a standard-conforming open toolchain? Otherwise I wouldn't even bother.
Looks that way. The basic architecture is ARM, which is quite well-supported by GCC and binutils. I managed to find a Technical Reference Manual on Cypress' website, which seems to have plenty of information on the hardware peripherals: http://www.cypress.com/?docID=36586 This thing seems to occupy an interesting point in the hobbyist ecosystem. The processor is several times more expensive than other chips with simi…
The mbed board is similar to the mini, but with an online IDE (not a fan) and community. There's not much difference in price there, at least not from the mbed suppliers here in the UK vs the kickstarter prices.