https://devzone.nordicsemi.com/f/nordic-q-a/11086/flash-app-compiled-with-gcc-using-dfu-with-bootloader-compiled-with-keilI compiled the bootloader and my app with keil arm and I can perform app flashing using DFU, then I compiled the app using gcc, then I can no longer flash using DFU. is there any issue with flashing an app compiled using gcc with a bootloader compileden-USTelligent Community 13Tue, 05 Jan 2016 16:09:31 GMThttps://devzone.nordicsemi.com/thread/41483?ContentTypeID=1Tue, 05 Jan 2016 16:09:31 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e0dc3dc4-1289-4d64-be80-d42fd805ab47makouda<p>yes I have 16KB, QFAA, i&#39;ll try to compile the bootloader using gcc too, thanks for your answer</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/41482?ContentTypeID=1Tue, 05 Jan 2016 16:08:06 GMT137ad170-7792-4731-bb38-c0d22fbe4515:357bd385-723c-491e-8495-73e70a20c9dfOle Bauck<p>I edited the answer, because it is only true for 16KB RAM. I guess you have that (QFAA or QFAB)?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/41484?ContentTypeID=1Tue, 05 Jan 2016 11:26:41 GMT137ad170-7792-4731-bb38-c0d22fbe4515:afbe32d3-ed5c-488f-b445-7a4a9d044634Ole Bauck<p>Flashing bootloader and application, one with GCC and one with Keil is not safe since the two compilers places the stack at different locations in RAM (GCC at the top of the RAM and Keil above the heap).</p> <p>The reason it does not work in this case is probably because bond sharing is stored at the top of the RAM if it is 16KB (more specific at address 0x20003F80), which is the same place as GCC places the stack. If this information is corrupted when the starting the DFU, the device will not connect automatically to the master and start the firmware transfer.</p> <p>Bottom line: Do not flash the bootloader and application with different compilers.</p><div style="clear:both;"></div>