Electronics > Repair

Fluke 8840A Faulty CPU

<< < (7/22) > >>

jaromir:
Great work. I'm really impressed by your progress so far.
Is there a chance you could release your work to public? I'm pretty sure that apart from being useful to folks with broken meters, it could also serve as source of knowledge to those ones being interested in how things work.

essele:
Hi Jaromir,

Absolutely -- I fully intend to release this all once I get it working. I'm starting to put things into github, and I'll switch it to public once it's in a usable state.

Lee.

essele:
Huge Progress...

- Implemented an interrupt mechanism (although more on this later)
- Finished off the port control stuff, and all the register read/write translation
- Added a debug mechanism to trap some stuff that shouldn't happen
- Fixed decrement-and-jump-if-not-zero instruction so it wan't increment-and-jump-if-zero (I must have been having a bad day)
- Fixed a few other instruction issues
- Banged my head against a brick wall for quite a while

... and ...

It works ...  mostly. It boots up, will accurately read DCV, DCA and Ohms, autorange works, front/rear selection works, it detects the lack of AC board (haven't tried that yet), the self tests will run (and pass) ... the calibration looks ok, so I suspect it's properly reading the existing cal ram.

How pleased am I!!!

There's still some work to do ... to get this far I've had to do some stuff in the interrupt handling that I shouldn't really have done, so I need to understand that a bit more, also some of the small buttons on the right cause an exception where it's trying to execute code at an address that doesn't exist. Then there's the serial stuff to check for the GPIB card.

I don't think the interrupts are working properly ... I don't see any timer interrupts at all, although that doesn't stop the basic functionality, the rate button doesn't do anything at the moment, so I suspect it might be related, and the execution of dodgy code does highlight I've got something else wrong somewhere, so once I find that other things may start working ok.

QUICK UPDATE:  I've fixed the bad code issue (was a mistake in the register-pair call code) so now all of the small buttons seem to work, I can change the rate, selected external trigger etc.

TheDefpom:
nice work, well done.

Johnny10:
Essele your talents are showing!

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod