nRF52 hard fault when running sd_softdevice_enable

Question

Received my nRF52 preview board yesterday and have been battling to get my S130 based nRF51 code running on it with the S132 soft device (the code is here: github.com/.../HomeKit including the current state of the NRF52 build under gcc/eclipse). 
 The code starts up and gets to the call to sd_softdevice_enable call in softdevice_handler.c. When it executes this call it always hits the HardFault_Handler seemingly regardless of the arguments I've tried it with. The last instruction it executes before the exception is "vmsr fpscr, r0" which I believe just moves the value of r0 into the floating point unit. 
 Any thoughts on what might be causing this greatly appreciated. 
 Thanks

RK · Accepted Answer

Is the FPU enabled? It's a while since I read the FPU unit documentation but I remember most instructions cause a fault if the FPU isn't. There's code to enable it in system_nrf52.c 
 I am however a little surprised the FPU is used in the softdevice since it's not required to be enabled and, apart from just generically setting things up to a known state, I can't see why the softdevice would use it. 
 Do you have an address of that instruction, any other addresses in the stack would be handy too, I was going to take a look at the assembler see what's going on. 
 I wish I had more time to play with my 52 devkit .. sigh.