DrAzzy thank you so much for your excellent list of potential causes of this error posted HERE. As a hardware designer I appreciate that there are limits to what the software can detect and report. I have this same error for about one week trying to upload "Blink" example on IDE 1.8.10, new Uno R3 clone, Win 8, CH340, drivers loaded and working, nothing connected to any pins. Board flashes red LED three times when reset and also when uploading (this shows that the bootloader and drivers are there, the board is being selected properly, USB is working). I have been to EVERY page on this problem, gone through them all step by step:
- tried every board and programmer,
- tried old boot loader,
- tried every baud rate,
- disabled anti-virus,
- loaded older version of IDE (1.8.4),
- turned off port FIFO buffers
and the problem remains. Plugged in a second brand new board and same problem. Clearly something is wrong here, but what?
I notice that response code changes. What does it mean? Is there any information about the problem to be gotten from it? I checked the AVRDUDE manual HERE and unfortunately not a single word on response codes.
Using Port : COM4
Using Programmer : arduino
Overriding Baud Rate : 115200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xba
This shows response code 0xba. I notice that the response code appears deterministic and is unchanged during the ten attempts, but it changes if I change something like board type, or port baud rate.
I changed the baud rate and now the response code has changed to 0x91:
Using Port : COM4
Using Programmer : arduino
Overriding Baud Rate : 115200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x91
Is there anything to be learned from the response codes? Thank you for any assistance.