Fuse was changed while writing flash!

Go To Last Post
4 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

So I have been having this behavior for a while with avrdude and USBASP where at the end of a flash writing procedure there is a verification error - every fuse bit is read as if it was 0x00.

Avrdude would then ask me if I would like to return the fuse to its original value - I pressed "no" and continued without giving too much attention to it until I was locked out of one of my chips! (an atmega328p)

I started working on a new chip and just now I realized - the lfuse used to be 0xff but now reads 0x17! The fuse was changed during this behavior - I was lucky I am not locked out of the chip again.

I also observed that this happens mostly when I set my programming voltage of the USBASP to 3.3V. What could be the reason of this behavior?

 

Could this fuse be written by some pointer mistake in the program I am burning?

 

Is there a way to "lock" the fuse bits so I dont accidentally get locked out of a chip again?

 

Here is a photo of the programming commands before and after the lfuse was changed -->

TO THE FINDER... THE ISLE OF KOHOLINT, IS BUT AN ILLUSION... HUMAN, MONSTER, SEA, SKY... A SCENE ON THE LID OF A SLEEPER'S EYE... AWAKE THE DREAMER, AND KOHOLINT WILL VANISH MUCH LIKE A BUBBLE ON A NEEDLE... CAST-AWAY, YOU SHOULD KNOW THE TRUTH!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I have seen this behavior with my ponyprog2000/ siprog as well as my tinyusb programmer on M328p and tiny84a, t85chips. I have no explanation of why, but the programming cycle is fairly sensitive. I have had them brick the chip and had to jump start them with an external clock more than once, with no apparent cause...( IE power glitches). In the worst case scenario the serial programming facility gets disabled.  

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I have seen that sort of thing with spring probes (pogo-pins) and an R-Pi (linuxspi, linuxgpio), but with a wired harness and an Arduino running the ISP sketch, I never saw that problem. It may have had to do with me shaking while holding the probes to the target.

Last Edited: Mon. Oct 12, 2020 - 12:07 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

If it is the result of intermittent connections, I really question the reliability of the program transfer.

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!