I reprogrammed the Atmega32u4 on my Arduino Uno Wifi Rev2 in order to use it as a human interface device, but I am now having difficulty programming the 4809 (through the 32u4 over UPDI) with the Arduino software. I have tried reprogramming the 32u4 with medbg_updi.hex from Atmel Studio and also Xplained Yourself Firmware from https://hackaday.io/project/162372-xplained-yourself.

I have had some success writing some smaller applications to the 4809 but when I try to program larger applications (which used to work before I fiddled with the 32u4), I now get verification error saying that there is a mismatch.

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0200
         0x08 != 0x0c
avrdude: verification error; content mismatch
avrdude: jtag3_edbg_signoff(): unexpected response 0x03, 0x80

When cross referencing with other working Uno Wifi Rev2 boards, they have

ICE firmware version: 1.19 (rel. 57)

while I now apparently have

ICE firmware version: 1.13 (rel. 43)

I do not see any place to find the updated/original firmware which came with my arduino. My thought is that the firmware is not available for direct download because it may be licensed from Microchip (Atmel) and not distributed/proprietary...

Please assist me if possible in restoring the full functionality of my Arduino Uno Wifi Rev2. Any insights would be appreciated.

  • look on the Arduino IDE directory tree .... on my PC the firmware is at arduino-1.8.12\hardware\arduino\avr\firmwares
    – jsotola
    Dec 3, 2020 at 5:32
  • 1
    @jsotola, that is for Uno not for Uno WiFi Rev 2 with a 4809
    – Juraj
    Dec 3, 2020 at 7:45


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