Reload Leonardo bootloader

Development Tools IDE 1.x
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Hi guys.
I'm new of this comunity, I have a problem and I don't know how to solve it.
I have an Arduino Leonardo on a LattePanda board and during a sketch upload, something went bad (I don't know why but it froze almost at the end) and then the board becames not accessible (Windows device manager reports: "USB device unknown").
I think that the bootloader was not written correctly and I would like to know how to reload it on the board.
I also have a Nano and a Leonardo and I know that I can use one of these boards as ICSP but I don't know the correct (and safe) procedure to do it.
Someone can help me?
Thank you.

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Before going the route of "burning the boot loader",

  1. When you press and release the reset button (some say that you need to double tap the reset button, that's not the case on my Leonardo) on the faulty Leonardo, does the L led pulse / fade? If no, you indeed can try to solve the issue by burning the boot loader.
  2. If yes, start the upload of an innocent sketch like the blink example. When the IDE reports the memory usage, press and release (or double tap) the reset button; you have a few seconds to do so.
  3. If this is succesful, try to upload blink again using the normal procedure (no reset of the board, the IDE will handle that for you).

Burning the bootloader should be straight forward but I have never done it with another Arduino.

  1. On a working board, select the correct board (Leonardo or Nano) in the IDE.
  2. Load the Arduino-as-ISP sketch.
  3. Disconnect from the PC and wire it according to instructions on the web. Be aware that if you use the Leonardo as the programmer, the ICSP pins are on the 6-pin header and not on the pins 11-13; same (obviously) applies to target Leonardo.
  4. Connect the programmer board (Nano or Leonardo) in the IDE
  5. Select the Leonardo as the board in tools -> menu; this is the target board (your faulty Leonardo)
  6. Select "burn boot loader" from the tools menu.
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Pressing the reset button the led lights on but when I release, it goes immediatly off.
I can't use the Arduino IDE because the board is not recognized as valid USB device so the virtual COM is not created and no comunication is allowed (the IDE one too).
I'll try the 2nd procedure.
Thank you.

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That's a bad sign. Did you disconnect everything from the board (only USB connected)?

You need one COM port; if your PC has a COM1, you can use that else you can hook up your Nano and select its port. It's just that there needs to be a port; I forgot to mention that.

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I would buy an ICSP programmer to upload the bootloader , leave the PC part off during this . You can only load the bootloader via this interface.

Don’t forget the power USB socket is only for powering , it is not a full usb , so you won’t see anything with that .
Can you see a com port for the Leonardo from the Latte panda PC part ( from the on board Arduino IDE)? The port often moves after rebooting

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Problem solved!
For 13,25 euro I bought an "USBTinyISP AVR programmer" and I did the job... :wink:
That's all folks. Thank you.

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