Hi all,
Well, I will start right at point, the "-F" option. How do i use it?
When trying to burn bootloader "Double check connections and try again, or use -F to override this check." comes up.
After googling did not help I set out to find a way to do it myself.
The instructions that follow should be tried at your own risk.
I will assume that you have hooked up your mcu(atmega328p) as required, i.e. on to a breadboard or directly onto another arduino and that the arduino IDE is installed on the C Drive. Make changes accordingly if you have installed it on some other drive.
Step 1. Locate avrdude.conf.
The avrdude.conf is in C:\Program Files\Arduino\hardware\tools\avr\etc
Copy the file and paste is directly in your C drive or any root directory.
Step 2. Open Command Prompt
Google it if you don't know how. And go to C drive root.
Step 3. Navigate to avrdude
Put the following on the Command Prompt window and press enter after every line.
cd Program Files
cd Arduino
cd hardware
cd tools
cd avr
cd bin
now that you have done the above your Command Prompt should look something like this
C:\Program Files\Arduino\hardware\tools\avr\bin>
Step 4. The -F Option
Now that you are here, copy the command and paste it on to command prompt and press enter.
I think it's almost never a good idea to use -F to override the signature check. Instead it's better to find the problem causing the signature verification to fail. However, I think I remember seeing reports on avrfreaks that' it's possible for the signature to get corrupted so it could be useful in that case I suppose.
99+% of the time, the problem is the connections (frequently, it comes from having a bootloader burned that is set to use a crystal, but no crystal connected, so no clock -> can't program it) or you're telling it to write a different chip than you have connected (wrong board selected or something). In the former case, -F will just result in getting a different error. In the latter case, you'll upload code compiled for the wrong chip and it won't work correctly.
In the remaining rare cases, the chip is malfunctioning (corrupted sig), and you will likely encounter other issues when trying to program it. I've had a chip do this, but it didn't work with -F either.
IMO, the avrdude message shouldn't refer to -F; it makes people think that -F is likely to be the solution to their problem, which it basically never is.
DrAzzy:
IMO, the avrdude message shouldn't refer to -F; it makes people think that -F is likely to be the solution to their problem, which it basically never is.
I know it doesn't work just by overriding the signature. I posted the tut just to satisfy the curiosity of people looking for the "-F" option.
Why not just tell them to enable verbose upload, try to do it through the IDE, and then copy-paste the AVRdude invocation on the first line? The IDE uses the full paths when it invokes avrdude, so you should just be able to paste that into notepad, add -F, and copy-paste the amended command into a command window...
But - point remains, I question why write a tutorial to instruct people how to waste time doing something that won't fix their problem.
DrAzzy:
But - point remains, I question why write a tutorial to instruct people how to waste time doing something that won't fix their problem.
To satisfy their curiosity. When you see the -F can override the signature verification but you don't know how to do it.
I myself googled for hours on how to use the -F option. There were no posts on how to it and in forums people asking the question were always said to their faces that you won't be able to do it, bla bla this bla bla that.
Let them try, may be it will work out for some one.