WDT issue with Atemga 328p 8Mhz (Mini pro)

Okay, I am stumped and nothing seems to work. I am on Arduino v 1.6.8. I have a custom arduino board that I made and its using an Atemga 328p (28 pin) chip.

I edited the boards.txt file to change the BOD fuse to 1.8v:

pro.menu.cpu.8MHzatmega328.bootloader.extended_fuses=0x06

The problem is this: When the WDT trips, the board is stuck in a restart loop. You can tell because pin 13 blinks constantly.

I read on many places that I needed to use Optiboot boot loader instead but that didn't work either. Optiboot worked fine when you didn't adjust the extended_fuse. After adjusting the fuse to 0x06 the WDT never actually recovered from a reset.

I am using "Arduino as ISP" with an Ardiuno mini Pro as my programmer (over SPI)

ANY help would be really appreciated!

I'm wondering what you would get if you turn off BOD entirely with extended_fuses=0x07.

Just curious, at what voltage are you running the ATmega328P?

What about just uploading the sketch using programmer instead of uploading through the bootloader, so you don't have a bootloader on there at all? (Upload Using Programmer function of the IDE). What does it behave like then?

Note that you have to do the Burn Bootloader function anyway, to set the fuses, then when you do Upload Using Programmer it will just upload the program and erase the bootloader, but the fuses will not be disturbed.

If this doesn't unstump you, I'm sure others on the forum who know more about this sort of thing would like to know what all of your fuse settings are and what version of what bootloader you are using and whether or not you used that bootloader to upload the sketch (or used your programmer), and of course would like to see your code (whole sketch) that has the problem.