Datasheet

Device Recovery
Sometimes, bad things unfortunately happen. Thankfully, 99% of the time it's purely a SW issue and the Bluefruit devices have a robust bootloader
with some fail safes that can almost always recover your device.
How to Recover a Bluefruit Board
1. Force DFU Mode at Startup
The first step is to force your board into a special bootloader mode, which will prevent any faulty user sketches or corrupted config data from
causing problems.
Connect the DFU pin to GND with a jumper cable, or if your board has a DFU button hold the button down when adding power to your board
(connecting the USB cable, etc.)
Once the device is powered, you should see a faster DFU MODE blinky pattern that lets you know you are in bootloader mode.
Now remove the jumper cable between DFU and GND (to prevent going into DFU mode when you reset)
Remove the jumper cable between DFU and GND once you are in DFU mode so that you exit it during the next reset!
2. Update the Bluefruit Firmware
Next, update your device to the latest Bluefruit firmware using the Bluefruit LE Connect app. We regularly fix bugs, and it's always a good idea to
be on the latest release.
You can perform a firmware update in DFU mode, although the Bluefruit board may appear as DfuTarg in the Bluefruit LE Connect app, and you
will will need to select the right firmware 'family' for you board.
Because bootloader mode is a fail safe mode and has a small subset of Bluefruit's features, we can't tell the Bluefruit LE Connect app very many
details about our HW. As such, you will need to indicate which firmware type to flash ... specifically, whether to flash the UART of SPI based
firmware. Be sure to select the right one, based on your product and the table below:
BLEFRIEND32 Firmware (UART, 32KB SRAM)
Bluefruit UART Friend V2 (http://adafru.it/edl)
Bluefruit LE UART Friend (http://adafru.it/tYD)
BLESPIFRIEND Firmware (SPI)
Bluefruit LE SPI Friend (http://adafru.it/fLp)
Bluefruit LE Shield (http://adafru.it/2746)
Bluefruit LE Micro (http://adafru.it/tYE)
Feather 32u4 Bluefruit LE (http://adafru.it/tYF)
Feather M0 Bluefruit LE (http://adafru.it/2995)
3. Flash a Test Sketch
Once the core Bluefruit firmware has been updated, flash a test sketch to the device from the Arduino IDE, such as the following blinky code:
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin LED_BUILTIN as an output.
pinMode(LED_BUILTIN, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}
4. Perform a Factory Reset
Once the core Bluefruit firmware has been updated, the final step is to perform a factory reset.
With the board still powered up, connect the DFU pin to GND
© Adafruit Industries
https://learn.adafruit.com/introducing-the-adafruit-bluefruit-le-uart-
friend
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