I want anyone to be able to build and contribute to this for free. Whether they run OpenBSD or FreeDOS, a 3970X or BCM2835. The problem being that the BLE stacks are not very maker friendly. Since I don't want to go through the headache of getting certifications, I've looked at what certified modules are about.
It boils down to three manufacturers really. The TI CC2541 Chip, The CSR1001/CSR1011 or the Nordic nrf51822 / nrf8001.
The TI chip doesn't have an embedded ARM, it has an 8051 based MCU. The problem is the bluetooth stack required comes with the £2k+ IAR software. The free kickstart version has a limit on binary size which is smaller than the BLE stack on its own.
There are some other stacks written for the TI chips / modules such as Bluegiga, but the quality, module availablilty and closed source nature of these third party stacks worrys me.
The CSR chips seem to sit behind sales representitives and I've even seen mentions of NDAs. Its a shame as they look like good chips. But they're out. Looks like CSR only want to play with the big boys. The dev kit is also quite expencive.
That leaves the Nordic chips. The nrf8001 is made to be configured by an external microcontroller using a serial based interface. The nrf51822 has its own low power ARM Cortex processor. Both look great. The tool downloads (including the BLE stack) sit behind a 'product key' on the site, but you get a key with the relatively cheap dev kits. These seem like the right choice here to me.
I've yet to find out if the nrf8001 interface can be developed without using their windows tool. But it should be a case of people not able to use the tool being able to do feature development and only requiring use of the tool if the BLE interface needs changing.
The nrf51822 has mbed support, including a high-level BLE interface. So I'm going to use that, at least until I find it has limitations or is not suitable.
So I'm going to prototype two systems:
1) nrf8001 + Low power ARM chip
And see which one holds up best for low power use, open-ness of the build system and price. In that order!