Half dead stk500

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

Hi Folks,

Weird problem with one of our STK500s. Was using it to program some student project boards and it has been playing up ever since.

When I power it up the LED doesn't go through its normal sequence but keeps flashing and I can't connect to the on board M32 - AVRstudio says no board connected. BUT if I remove the power jumper and re-power the board, LED goes through normal startup sequence ok and I can then reconnect the power jumper live and everything works ok. Have tried removing the micro but that makes no difference and it is programming okay.

Anybody got any ideas of what I've cooked?

Thanx.
Murdo.

There are already a million monkeys in front of a million keyboards, and the internet is nothing like Shakespeare!

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

There could be an issue with the external circuits, disconnect all the connections and try to do manual firmware upgrade of the tool to be confident on the tools firmware.

This manual firmware upgrade can be done by going through the STK500 User's guide.

After manual firmware upgrade, check your connection for any short circuit and then connect one after the other to identify which connection is creating the issue.

Do not connect programming cable with other external circuits connected to STK500.

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

Mine has no shunts on PJMP headers and I use wall wart for power. I have not looked at STK500 schematics in a long time so I am not sure what PJMP does but it seems like you leave it open.

Edit:

For Socket32 Green you need to connect to SPROG2 to ISP6PIN with a jumper ribbon. Do you have that in place and a part installed in that socket?

Also are you using a plug in crystal? If yes, did it fall out of the plug?

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

Thanks for the ideas so far guys but already tried all the above. From memory it is the jmper called VTARGET which seems to allow the board to startup ok (status led cycles and settles on green)

Board is fully isolated from other circuits, no crystal, default jumper settings, using the 6 pin isp connector - pretty boring setup...

For some reason I can't upgrade the firmware in any of our boards but they should all be the same ver (whatever that is)

It seemed to start when we were trying to program a home brew pcb circuit and I'm wondering if I've blown something - anybody seen an STK500 play funny before?

Normally they're rock solid and this is the first one we've cooked in 4 years.

Murdo.

There are already a million monkeys in front of a million keyboards, and the internet is nothing like Shakespeare!

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

That jumper connects the target power regulator output out to the target and an transistor LED indicator for target power. U601/LM317 regulator who's control pin is driven by LM358. Looks like you could measure the regulator with the shunt pulled. You would have to start a program cycle for the target power to be on maybe?
There are Caps out there on VTG rail probably at each target socket. Maybe those electrolytics have dried out. Look for one that is bulging or leaking.

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

>> alwelch

Thanx for the ideas: I'll try looking there when I get back to college in a few days.

Murdo.

There are already a million monkeys in front of a million keyboards, and the internet is nothing like Shakespeare!