Memory concerns when performing a live DFU?

[Mitch996]

Hello, I'm looking into this particular issue and are now having some concerns. Namely:

1. My firmware size currently stands at 30k. It's not big, but definitely not small. For a successful dual bank update, I may need 30 X 2 (most ideal scenario) KBs of memory space. The problem is, a typical device, nrf51422 for example, has only a maximum 256kb of "embedded flash program memory". Considering the fact that an S110 softdevice alone is 249 kb in size (hex file, which suggests that the actual code will be smaller), will there be a problem when there is not enough memory to do a dual bank live DFU?

2. If there is not enough built-in memory to perform a live dual bank DFU, will an external flash chip have any complications? Is there something I must be cautious about?

3. Is there a configuration guide somewhere to which I can refer, on seamlessly integrate external SRAM and FLASH chips with embedded ones that came with the chip? To be more specific, how to properly configure keil IDE?

[bjorn-spockeli]

Hi Mitch,

The S110 v8.0.0 requires 96kB (0x18000 bytes) and the dual bank bootloader requires 16kB, which means that you're left with 144kB of application space when using a 256kB flash nRF51x22 variant, which is enough to perform a dual bank DFU of an application upto 72kB. Thus, you do not need to add external flash memory.

Best regards

Bjørn

[Mitch996]

Thanks Bjørn, will mark your answer as "answered" in the future if no other question arises.