Mega8's fail to prog with AVRISP

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

I have a problem with some pcbs that use a Mega8 and are programmed via stk500 and AVR ISP + 6 pin connector.
When I look at MISO on the CPU, it is low and only toggles up to about 0.5V when I press program.A working one is at 4V and toggles properly.
There is nothing I can do to get this going. All attempts result in the standard error message.
Is there anyway these devices could have 'locked up' and can no longer be programmed via ISP?

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

Have the "bad" boards been programmed before? Or are they brand-spanking new?

If you can switch back & forth between the "good" and "bad" boards, that kind of eliminates the STK500, the connector on the STK500, and any other mounted chips, etc.

If they are not brand-new chips, then they >>could<< have had the RSTDISBL fuse programmed. (SPIEN as well, but that is harder to do.)

Does the Vcc level look OK on the target boards?

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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

Hi!
I also suspect that RSTDISBL fuse has been (accidentally) programmed (=0), leading to the impossibility of further programming the chip via ISP.

Real men don't use backups, they post their stuff on a public ftp server and let the rest of the world make copies.

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

No, they were programmed before.Everything else is good, STK/AVR as I can swap between good and bad anytime.Vcc is ok . Reset gets pulled low, mosi, clk is good.
I did find an error on my programmer adapter- 0v was missing to my target board, some programmed some didn't. Most that 'appeared' to program, and verify, failed to work.It's these that I can't re-program.
Simple test I guess is to lift them and put them into the parallel programmer....