I've read every thread about this problem.
Related problems:
-Can't update firmware 16u2
-can't get to dfu mode after connect pins Reset and GND on 16u2 side ISCP pins
My second purchase and again failed with uploading firmware using avrdude
For my defense I'm doing all correct by the book.
Here is my code for terminal in Mac
cd /Users/michalkulas/Library/Arduino15/packages/arduino/hardware/avr/1.8.6/firmwares/atmegaxxu2/
avrdude -p m16u2 -F -P /dev/cu.usbserial-22110 -c avrisp -b 19200 -U flash:w:Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Rev3.hex -U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0F:m
And it's working for my greenish board aka original.
The problem with other board is: not recognizing device signature.
avrdude: AVR device initialized and ready to accept instructions
Reading | ################################################## | 100% 0.02s
avrdude: Device signature = 0x000000 (retrying)
Reading | ################################################## | 100% 0.02s
avrdude: Device signature = 0x000000 (retrying)
Reading | ################################################## | 100% 0.02s
avrdude: Device signature = 0x000000
avrdude: Yikes! Invalid device signature.
avrdude: Expected signature for ATmega16U2 is 1E 94 89
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Rev3.hex"
avrdude: input file Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Rev3.hex auto detected as Intel Hex
avrdude: writing flash (15668 bytes):
Writing | ################################################## | 100% 4.77s
avrdude: 15668 bytes of flash written
avrdude: verifying flash memory against Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Rev3.hex:
avrdude: input file Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Rev3.hex auto detected as Intel Hex
Reading | ################################################## | 100% 2.52s
avrdude: verification error, first mismatch at byte 0x0000
0x00 != 0x90
avrdude: verification error; content mismatch
avrdude done. Thank you.
And for orignal:
avrdude: AVR device initialized and ready to accept instructions
Reading | ################################################## | 100% 0.02s
avrdude: Device signature = 0x1e9489 (probably m16u2)
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Re22v3.hex"
etc.
What can be done?
Any help