https://devzone.nordicsemi.com/f/nordic-q-a/6463/how-to-implement-2-bootloadersHi Team, I would like to implement a second bootloader to program an external serial Flash chip. Currently using S110 V7.1. My current thinking is to create another self contained application in BANK_0 (I should have the space) which when run willen-USTelligent Community 13Sat, 11 Apr 2015 02:05:28 GMThttps://devzone.nordicsemi.com/thread/22549?ContentTypeID=1Sat, 11 Apr 2015 02:05:28 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3d9d1bfc-ed3a-4838-be0d-febe54926c95Clem Taylor<p>I had the same issue.</p> <p>Initially I was going to extend the START packet to include an extra optional length field. But I needed to be able to test the SPI upgrade before our app was written. So instead I added data to init packet that specifies the SPI partition data.</p> <p>My SPI flash is 2MB, the worst case upgrade time really sucks.</p> <p>If I had it to do over again, I suspect I would drop the DFU bootloader and go with a bootloader that only knows how to copy data from SPI flash into nrf51 flash. That way the bootloader wouldn&#39;t be tied to the softdevice and I would end up with more internal flash to work with. The application would download the new application (over time, no hurry) and once all the data is validate, reboot with a GPREGRET command to swap in new data.</p><div style="clear:both;"></div>