Hi mattyt,
I'm glad to hear that you have received your new kit
If you haven't already got something up running, i will try to answer your comments and questions as best as i can. It would be great to get this board up running!
The repository name "nrf5_no_sdk" might also be a bit misleading. Softdevices are still used in some of the build targets providing Bluetooth LE functionality. However, this can be downloaded seperatly as it cannot be re-distributed as part of a github repo, license wise. Also, the nrf51/52 could be useful as a target without Softdevice as well, for proprietary 2.4Ghz protocols etc. Or even without radio at all. What the name however indicates is that the micropython port does not depend on an SDK. No components like libraries or HAL drivers has been used from a nordic SDK, making the port standalone.
By default, the nrf5_no_sdk is targetting pca10040, which is using the same chip variant as the feather; nrf52832. Hence, you can try to use some of the existing build targets for pca10040 as a starting point. The application with default configuration currently has these sizes:
142020 (make / no softdevice use, and starting at 0x0)
151920 (make SD=s132 - softdevice used, 1 peripheral and starting at 0x1f000)
152448 (make SD=s132 - softdevice used, 1 peripheral and Bluetooth REPL activated, starting at 0x1f000)
So, the SD=s132 compiled variants should fit just by a few bytes.
Do you have the address of application and bootloader on the Feather?
If the application is positioned on above the softdevice (assuming s132 - 0x1f000) and bootloader in top of flash, then it maps quite well to the pca10040. The nrf52832_512k_64k_s132.ld linker script will be used if SD=s132 is defined, offsetting to 0x1f000. Possible, creating the hex file that you want
Does the feather provide UART over USB?
If not, using the Bluetooth LE REPL should work out-of-the box even on this target board. Bluetooth REPL is activated in bluetooth_conf.h as MICROPY_PY_BLE_NUS (1).
When it comes to whether the repo contains any DFU implementation, the answer is sadly No. It would have been a very nice feature to provide. Probably even needed in the long run.
One additional note:
If you intend to flash using Segger, only use the "flash" Makefile target, and not the "sd" target as it the latter target will do an 'eraseall' on the chip. Unless you have access to the bootloader firmware i would suggest that for the first flashes you do it manually, to preserve the bootloader and softdevice. Examples for sector flashing of application can be located in the Makefile.
Cheers,
Glenn