Flash and Radio

Question

Hello, 
 I've read a lot about trouble people had when they used bluetooth and flashed the rom without using the propper softdevice APIs. 
 What is the issue with concurent use of the flash and the radio? Is it just that the ble stack uses the flash too and that the CPU halts during the flash operation and that this would cause the BLE stack to miss critical timings? 
 I ask because I want to use the radio and the flash hardware, without the softdevice and wonder if there might be something I'm not aware of. 
 TIA,
Torsten

Vidar Berg · Accepted Answer

Hello, 
 The CPU is halted during flash operations as you mentioned, which is why the stack attempts to schedule it in-between radio events in order to allow a BLE link to be maintained at the same time( SD flash API ). Note that the problem is not the radio activity in itself, but CPU processing tied to it (pre-processing,etc.). 
 It's normally not a problem to use the NVMC directly unless there are any critical tasks that can't be blocked. The time it takes to perform a particular flash operation is listed in the the NVMC chapter of the product specification for nrf51.