Datasheet

Factory Reset

The Bluefruit nRF52 Feather has an optional FRST pad on the bottom of the PCB.

If you brick your device, you can solder a wire to the FRST pad, connecting it to GND. When a GND state is detected at

power up the following actions will be performed:

The user application flash section will be erased

The user 'App Data' section that stores non volatile config data will be erased

This will cause the device to enter serial bootloader mode at startup, and the user sketch or config data that caused

the device to stop responding should be removed.

Advanced: OTA DFU Bootloader

While this is only recommended for advanced users, you can also force OTA (Over The Air) DFU bootloader mode to

enable OTA updates using BLE and Nordic's proprietary update protocol (which is support by both Nordic mobile apps,

and out own Bluefruit LE Connect).

To force OTA DFU mode, set both FRST and DFU to GND at startup. Power cycling the board will cause the device to

boot up into OTA DFU mode.

Advanced: Upgrading an Existing Bootloader

The Adafruit Feather nRF52 Bootloader binary contains not only the DFU code, but also the Bluetooth stack

(a.k.a SoftDevice) to make sure they work together reliably. To get the latest and greatest features from the stack such

as Bluetooth 5.0 with higher throughput, increased broadcast capacities or larger MTU it is necessary to upgrade

Bootloader to get the latest stack.

Luckily the Bluefruit nRF52 Bootloader can be upgraded/downgraded without any additional hardware, and we can

even do that right in Arduino IDE without at risk of typos or common user errors.

First select the Bootloader version that you want to upgrade under Tools->Bootloader. Then select "Bootloader DFU

for Bluefruit nRF52" for Tools->Programmer

Be sure to disconnect the pin from GND after a successful factory reset!

This option is not actively support nor recommended by Adafruit, and we are still working on making this as

safe as possible for users via our Bluefruit LE Connect application. Use OTA DFU at your own risk knowing

you can brick your device and may need a Segger J-Link or similar device to regain control of it!

Upgrading the Bootloader is only possible from BSP release 0.8.0 and higher.

Close the Serial Monitor before you click "Burn Bootloader". Afterwards, you shouldn't close the Arduino IDE,

unplug the Feather, launch Serial Monitor etc ... to abort the process. There is a high chance it will brick your

device! Do this with care and caution.