Hi all,

I'm trying to repair a board that has a Motorola mc68hc11f1 processor (running in expanded mode) from a Am29f010b.

It runs a tractor dash board and has quite alot of stuff on it but won't start up. I first changed the processor as I suspected bad connections to it but still have the same problem.

The processor pulls it's reset pin low regularly, I can't quite measure it as its a small pulse that disappears on my scope when I get the right timescale to measure but would guess it's around 0.5-1s.
According to the data sheet this is either the wdt or cop reset.

Either way it's resetting itself every second or so.

I scoped each data line on the micro along the clock pulse from pin E

It looks to me like only 2 of the 8 data lines are carrying data? Would that be right? If so I assume that probably means the eeprom chip is done for and not supplying the data the processor needs to run?

If so that's the end of the job as the firm who made it have ceased trading and I've no way of getting hold of the program.

Thanks Geoff

 

If this is the end of life of the board you can send me the Am29f010b and I will attempt to read it.
If it is dead then you've reached a dead end.

 

Thank you that's very kind, where abouts are you in the world!

Only issue I can see is removing it without finishing it off!

 

Thank you that's very kind, where abouts are you in the world!

Only issue I can see is removing it without finishing it off!

I am across the pond. I will be in the UK in Sept. What is the package of the Am29f010?

 

It's a plcc so might be able to get it off with hot air gun?!

 

If it is 32-pin plcc then isn't it in a socket?
Can you post photos of the chip and the whole board?

 

No it's soldered on, as was the processor.



Would your gut feeling be that the eeprom is the issue?

Thanks Geoff

 

Ok, got it.
I don't have PLCC sockets for that chip. That makes it difficult to diagnose.

If the watchdog is being triggered I don't know if this would be visible on the NRST pin. I would have to read up on this.

 

I am going to hazard a guess that something external is triggering NRST.
I will have a look at this. I am away for the next 5 days.

 

I'd wondered that, there is a brown out detection chip on the reset pin so I cut the track to that and the reset pulse remained.
I will have a prod around later and check it doesn't go anywhere else I haven't found.

I'm starting to run out of time a bit on this as I do need the machine soon so may have to stomach buying a new dash

 

Just to confirm, I cut the track for the reset pin tight to the processor, the pulse on the reset track disappeared (there is a weak pull up on this circuit) the reset pin is now low as it's disconnected from the pull up.
I assume this means the processor is producing the pulse.

Cheers Geoff

 

I was just about to give up on this and order a new dash, then I found a forum which has a dump of the AM29FD10B from the Vansco dash.

I'm just waiting to be approved to download it then I might put a new one on a try to program it?!

 

I've rolled the dice and paid £25 to join the forum, ordered a new memory chip, download a rar file from a link on the forum which I think I'll open on a unimportant computer first !!

Any goot tutorials for programming these, I have got a app note that I need to study more but it looks like can be programmed with a serial lead? And not much else?

Cheers Geoff

 

I looked into the MC68HC11F1 docs.

Yes, it does say that a watchdog timer reset will generate a LOW signal on the /RESET pin.
This suggests that bad code in the ROM can trigger signals on the /RESET pin.

As for programming the Am29F010B, that is not going to be easy. I have to look up what this will entail.

 

Thanks for looking at this, attached is the app note I found for programming, do you think this will be suitable?

Or am I better to buy a programmer (there a few on Amazon etc with sockets that should fit) and program the AM29FD10B before I fit it to the board?

Thanks again Geoff

 

Just been looking at them in more detail, the tl866ii lists the AM29F010B as a compatible device.
I have the binary file for it (hopefully!)
and a new AM29F010B on its way.

The programmer looks pretty useful anyway so I might order one. It's the second time I think I need one now!

Cheers

 

Programmer has arrived!
Peeled the eeprom off the board with the hot air gun and dropped it into the programmer, it reads ok, but using a program called hdx to compare the 2 binary files (download and actual) there are large sections of of data set to FF where the download has data?!

Where there is data the 2 appear the same?

Does eeprom fail in this way? I'm tempted to reprogram it with the download data but think I ought wait for the new eeproms to turn up?!

 

Possible.
Write out the address sections where the data read is FF.
Memory is organized in pages. If the FF section align with a page, that could be the reason.

 

Just a quick update!
New am29f010b has arrived, I programmed it with the bin file I found on line, my socket wouldn't match up with the solder pads on the board so I soldered the chip in , powered up and.....
Nearly succes, the dash is alive but as the download was from a different model and a old tractor it has 100000kms on it and won't talk to the transmission (reports a can bus fault and I'm not even sure my transmission has can bus)

So it's back to the binary files, the one I pulled out my dash is missing a chunk of data from 4000-8000 then another chunk a bit later on.

There is then a set of address that match and have different data, I think I might make one file from the 2 as the later data is I believe configuration data and the earlier is program data.

So it's now a wait for a socket that will fit so I can reprogram it more easily.

Cheers Geoff

 

Can you send me the file from the ROM and the file you downloaded?
I can have a look at the two. For security reasons, you can send it to me via PM or you can set up a shared drop box.