Bit rot in micro controllers?...

[Joerg]

Just repaired our fridge when, according to Murphy\'s law, the next
appliance became shaky. Our pellet stove has twice refused to be turned
off. Unfortunately, instead of analog it\'s all buttons that are operated
via port pins of a micro controller. Pressing several of those
willy-nilly made the on/off button work, at least long enough to turn it
off. When the circuit board is cold the botton always works but not when
warm after running the stove overnight.

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Martin Rid]

Joerg <news@analogconsultants.com> Wrote in message:r
> Just repaired our fridge when, according to Murphy\'s law, the next appliance became shaky. Our pellet stove has twice refused to be turned off. Unfortunately, instead of analog it\'s all buttons that are operated via port pins of a micro controller. Pressing several of those willy-nilly made the on/off button work, at least long enough to turn it off. When the circuit board is cold the botton always works but not when warm after running the stove overnight.The micro controller is a Winbond W78E52BF-24 running on a 12MHz crystal. It is based on what they call electrically erasable MTP-ROM with which I assume they mean EEPROM. Date code is 2001 and that is also when we had that pellet stove installed.Can these things develop loss of flash memory (bit rot) this soon, after only two decades? Any remedy short or reprogramming or is it toast?-- Regards, Joerghttp://www.analogconsultants.com/

--
Probably a bad switch or solder connection from thermal cycling.

Cheers


----Android NewsGroup Reader----
https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html

 

[Rick C]

On Saturday, December 11, 2021 at 2:58:14 PM UTC-5, Martin Rid wrote:

Joerg <ne...@analogconsultants.com> Wrote in message:r
Just repaired our fridge when, according to Murphy\'s law, the next appliance became shaky. Our pellet stove has twice refused to be turned off. Unfortunately, instead of analog it\'s all buttons that are operated via port pins of a micro controller. Pressing several of those willy-nilly made the on/off button work, at least long enough to turn it off. When the circuit board is cold the botton always works but not when warm after running the stove overnight.The micro controller is a Winbond W78E52BF-24 running on a 12MHz crystal. It is based on what they call electrically erasable MTP-ROM with which I assume they mean EEPROM. Date code is 2001 and that is also when we had that pellet stove installed.Can these things develop loss of flash memory (bit rot) this soon, after only two decades? Any remedy short or reprogramming or is it toast?-- Regards, Joerghttp://www.analogconsultants.com/

--
Probably a bad switch or solder connection from thermal cycling.

+1`

Don\'t know why the EEPROM would be suspect first. Wouldn\'t that produce a more permanent glitch? I suppose it could become temperature sensitive. Maybe the stove manufacturer has a note on this issue or even a recall.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[Joerg]

On 12/11/21 12:30 PM, Rick C wrote:

On Saturday, December 11, 2021 at 2:58:14 PM UTC-5, Martin Rid wrote:
Joerg <ne...@analogconsultants.com> Wrote in message:r
Just repaired our fridge when, according to Murphy\'s law, the next appliance became shaky. Our pellet stove has twice refused to be turned off. Unfortunately, instead of analog it\'s all buttons that are operated via port pins of a micro controller. Pressing several of those willy-nilly made the on/off button work, at least long enough to turn it off. When the circuit board is cold the botton always works but not when warm after running the stove overnight.The micro controller is a Winbond W78E52BF-24 running on a 12MHz crystal. It is based on what they call electrically erasable MTP-ROM with which I assume they mean EEPROM. Date code is 2001 and that is also when we had that pellet stove installed.Can these things develop loss of flash memory (bit rot) this soon, after only two decades? Any remedy short or reprogramming or is it toast?-- Regards, Joerghttp://www.analogconsultants.com/

--
Probably a bad switch or solder connection from thermal cycling.

I don\'t think so because several other buttons also fail when warm and
they aren\'t set in a matrix. The solder job on the board looks very good
and it all ohms out well.

+1`

Don\'t know why the EEPROM would be suspect first. Wouldn\'t that produce a more permanent glitch? I suppose it could become temperature sensitive.

That\'s why I am asking, to see whether this is a sign of impending
\"permanent\" bit rot. I don\'t know much abou this EEPROM business.

... Maybe the stove manufacturer has a note on this issue or even a recall.

I doubt they really care about that. There was another issue with this
stove right after installation. I really had to rock the boat until they
admitted it and actually sent out a correction note to installers with
my mod in there (exhaust temp sensor).

Worst case I may have to \"analogize\" the whole enchilada but that would
require a lot of reverse engineering and work. Of course, then it would
last forever.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Jonathan Winter]

On Saturday, 11 December 2021 at 15:45:03 UTC-5, Joerg wrote:

On 12/11/21 12:30 PM, Rick C wrote:
On Saturday, December 11, 2021 at 2:58:14 PM UTC-5, Martin Rid wrote:
Joerg <ne...@analogconsultants.com> Wrote in message:r
Just repaired our fridge when, according to Murphy\'s law, the next appliance became shaky. Our pellet stove has twice refused to be turned off. Unfortunately, instead of analog it\'s all buttons that are operated via port pins of a micro controller. Pressing several of those willy-nilly made the on/off button work, at least long enough to turn it off. When the circuit board is cold the botton always works but not when warm after running the stove overnight.The micro controller is a Winbond W78E52BF-24 running on a 12MHz crystal. It is based on what they call electrically erasable MTP-ROM with which I assume they mean EEPROM. Date code is 2001 and that is also when we had that pellet stove installed.Can these things develop loss of flash memory (bit rot) this soon, after only two decades? Any remedy short or reprogramming or is it toast?-- Regards, Joerghttp://www.analogconsultants.com/

--
Probably a bad switch or solder connection from thermal cycling.

I don\'t think so because several other buttons also fail when warm and
they aren\'t set in a matrix. The solder job on the board looks very good
and it all ohms out well.
+1`

Don\'t know why the EEPROM would be suspect first. Wouldn\'t that produce a more permanent glitch? I suppose it could become temperature sensitive.
That\'s why I am asking, to see whether this is a sign of impending
\"permanent\" bit rot. I don\'t know much abou this EEPROM business.


... Maybe the stove manufacturer has a note on this issue or even a recall.


I doubt they really care about that. There was another issue with this
stove right after installation. I really had to rock the boat until they
admitted it and actually sent out a correction note to installers with
my mod in there (exhaust temp sensor).

Worst case I may have to \"analogize\" the whole enchilada but that would
require a lot of reverse engineering and work. Of course, then it would
last forever.
--
Regards, Joerg

http://www.analogconsultants.com/

Maybe the switch contacts are getting corroded. This happened to my Maytag front loader washing machine. The power switch is directly above the soap tray and gets corroded from the bleach fumes. I put a drop of mineral oil on the button shaft where it worked its way into the switch. After a couple of applications the mineral oil reached the contacts and cleaned them. Now the switch works perfectly with no sign of degredation. I think the mineral oil is protecting the contacts from the fumes.

 

[Jeff Liebermann]

On Sat, 11 Dec 2021 11:51:11 -0800, Joerg <news@analogconsultants.com>
wrote:

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

MTP-ROM is suppose to be good for up to 1 million write cycles:
<https://anysilicon.com/semipedia/multi-time-programmable-mtp-memory-ip/>
However, after only 1,000 erase/write cycles, the erase/write voltages
begins to change. See Fig 15:
<https://onlinelibrary.wiley.com/doi/full/10.4218/etrij.15.0114.1428>
\"After 1,000 erasing/writing cycles at a program
voltage of ±6 V with a write time of 5 ms, the
VT of a programmed cell is lowered from 2.92 V
to 2.9 V and the VT of an erased cell is raised
from -1.3 V to -0.5 V.\"
If the MTP-ROM device initially worked properly, and then slowly
started failing to recognize button pushes, that might be the problem.
Assuming you run the pellet burner for half the year and turn it
on/off once per day, that would be:
180 days * 1 cycle/day * 20 years = 3,600 erase/write cycles
which might be sufficient to see the problem.

Note: I don\'t have any experience with the Winbond W78E52BF-24.
Therefore, I don\'t know if it has this problem.


--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Sylvia Else]

On 12-Dec-21 11:14 am, Jeff Liebermann wrote:

On Sat, 11 Dec 2021 11:51:11 -0800, Joerg <news@analogconsultants.com
wrote:

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

MTP-ROM is suppose to be good for up to 1 million write cycles:
https://anysilicon.com/semipedia/multi-time-programmable-mtp-memory-ip/
However, after only 1,000 erase/write cycles, the erase/write voltages
begins to change. See Fig 15:
https://onlinelibrary.wiley.com/doi/full/10.4218/etrij.15.0114.1428
\"After 1,000 erasing/writing cycles at a program
voltage of ±6 V with a write time of 5 ms, the
VT of a programmed cell is lowered from 2.92 V
to 2.9 V and the VT of an erased cell is raised
from -1.3 V to -0.5 V.\"
If the MTP-ROM device initially worked properly, and then slowly
started failing to recognize button pushes, that might be the problem.
Assuming you run the pellet burner for half the year and turn it
on/off once per day, that would be:
180 days * 1 cycle/day * 20 years = 3,600 erase/write cycles
which might be sufficient to see the problem.

Note: I don\'t have any experience with the Winbond W78E52BF-24.
Therefore, I don\'t know if it has this problem.

It doesn\'t seem likely that the system is writing its flash every time
it is turned on, or off. Indeed, it doesn\'t sound like it has a reason
to write its flash at all, with flash being used merely because it was
cheaper than getting a custom ROM.

Sylvia

 

[Jeff Liebermann]

On Sun, 12 Dec 2021 11:26:42 +1100, Sylvia Else <sylvia@email.invalid>
wrote:

On 12-Dec-21 11:14 am, Jeff Liebermann wrote:
On Sat, 11 Dec 2021 11:51:11 -0800, Joerg <news@analogconsultants.com
wrote:

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

MTP-ROM is suppose to be good for up to 1 million write cycles:
https://anysilicon.com/semipedia/multi-time-programmable-mtp-memory-ip/
However, after only 1,000 erase/write cycles, the erase/write voltages
begins to change. See Fig 15:
https://onlinelibrary.wiley.com/doi/full/10.4218/etrij.15.0114.1428
\"After 1,000 erasing/writing cycles at a program
voltage of ±6 V with a write time of 5 ms, the
VT of a programmed cell is lowered from 2.92 V
to 2.9 V and the VT of an erased cell is raised
from -1.3 V to -0.5 V.\"
If the MTP-ROM device initially worked properly, and then slowly
started failing to recognize button pushes, that might be the problem.
Assuming you run the pellet burner for half the year and turn it
on/off once per day, that would be:
180 days * 1 cycle/day * 20 years = 3,600 erase/write cycles
which might be sufficient to see the problem.

Note: I don\'t have any experience with the Winbond W78E52BF-24.
Therefore, I don\'t know if it has this problem.

It doesn\'t seem likely that the system is writing its flash every time
it is turned on, or off. Indeed, it doesn\'t sound like it has a reason
to write its flash at all, with flash being used merely because it was
cheaper than getting a custom ROM.

Sylvia

Maybe you\'re right. I guess I have to dig deeper.

The other symptoms (sensitivity to heat and other inputs having
problems) seem (to me) to point to a chip problem. The data sheet
indicates that the 8 KBytes of electrically erasable/programmable
MTP-ROM is for program memory.
<https://www.digchip.com/datasheets/download_datasheet.php?id=1048062&part-number=W78E52B-24>
The device also has 256 bytes of scratch pad RAM. Therefore, there is
no need to use the MTP-ROM as a non-volatile scratch pad, unless the
chip is also doing something write intensive, such as data logging.
The chip is capable of addressing up to 64 KBytes of external RAM. If
this is static RAM, then it could be used for saving system status
when the power is cycles. If it\'s volatile (dynamic) RAM, it would
require a battery. If only a few things need to be stored (auger
position, burn time, power status, etc), it could probably be done in
the chip\'s built in 256 byte scratch pad RAM. If most data is being
stored, it would be very tempting to save it to the MTP-ROM area.

I still like my first guess(tm), but to be certain, I would need to
know more about the controller board and what the chip is doing.

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Michael Schwingen]

On 2021-12-11, Joerg <news@analogconsultants.com> wrote:

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

Quite probably yes - I remember a series of TFT monitors some years ago
where that happened to the on-board controller. Raising/lowering VCC may
help a bit (if it is not read-protected, you might try to read the memory at
different VCC levels and see if you can get correct data, and then
re-program).

cu
Michael

 

[Martin Brown]

On 11/12/2021 19:51, Joerg wrote:

Just repaired our fridge when, according to Murphy\'s law, the next
appliance became shaky. Our pellet stove has twice refused to be turned
off. Unfortunately, instead of analog it\'s all buttons that are operated
via port pins of a micro controller. Pressing several of those
willy-nilly made the on/off button work, at least long enough to turn it
off. When the circuit board is cold the botton always works but not when
warm after running the stove overnight.

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

My instinct would be there is a failing electrolytic capacitor somewhere
that is allowing the CPU to see glitches that blind it to the on/off
button. Some polling algorithms are a bit stupid so another button stuck
down might also have the same effect. You might have hoped that there
would be a failsafe emergency stop button on something that makes fire!

I never trust CPUs for safety interlocks! There is good reason.

--
Regards,
Martin Brown

 

[Tom Gardner]

On 12/12/21 00:26, Sylvia Else wrote:

It doesn\'t seem likely that the system is writing its flash every time it is
turned on, or off. Indeed, it doesn\'t sound like it has a reason to write its
flash at all, with flash being used merely because it was cheaper than getting a
custom ROM.

Such things are done in some instruments, to save the
current control settings between sessions.

 

[Jasen Betts]

On 2021-12-12, Sylvia Else <sylvia@email.invalid> wrote:

On 12-Dec-21 11:14 am, Jeff Liebermann wrote:
On Sat, 11 Dec 2021 11:51:11 -0800, Joerg <news@analogconsultants.com
wrote:

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

MTP-ROM is suppose to be good for up to 1 million write cycles:
https://anysilicon.com/semipedia/multi-time-programmable-mtp-memory-ip/
However, after only 1,000 erase/write cycles, the erase/write voltages
begins to change. See Fig 15:
https://onlinelibrary.wiley.com/doi/full/10.4218/etrij.15.0114.1428
\"After 1,000 erasing/writing cycles at a program
voltage of ±6 V with a write time of 5 ms, the
VT of a programmed cell is lowered from 2.92 V
to 2.9 V and the VT of an erased cell is raised
from -1.3 V to -0.5 V.\"
If the MTP-ROM device initially worked properly, and then slowly
started failing to recognize button pushes, that might be the problem.
Assuming you run the pellet burner for half the year and turn it
on/off once per day, that would be:
180 days * 1 cycle/day * 20 years = 3,600 erase/write cycles
which might be sufficient to see the problem.

Note: I don\'t have any experience with the Winbond W78E52BF-24.
Therefore, I don\'t know if it has this problem.


It doesn\'t seem likely that the system is writing its flash every time
it is turned on, or off. Indeed, it doesn\'t sound like it has a reason
to write its flash at all, with flash being used merely because it was
cheaper than getting a custom ROM.

Sylvia

It could be storing thermostat settings in eeprom, but that seems
unrelated to the fault reported.


if it doesn\'t like the heat the fault is probably some heat sensitive part,
an electrolytic capacitor for example.

--
Jasen.

 

[Tom Gardner]

On 11/12/21 19:51, Joerg wrote:

Just repaired our fridge when, according to Murphy\'s law, the next appliance
became shaky. Our pellet stove has twice refused to be turned off.
Unfortunately, instead of analog it\'s all buttons that are operated via port
pins of a micro controller. Pressing several of those willy-nilly made the
on/off button work, at least long enough to turn it off. When the circuit board
is cold the botton always works but not when warm after running the stove
overnight.

The micro controller is a Winbond W78E52BF-24 running on a 12MHz crystal. It is
based on what they call electrically erasable MTP-ROM with which I assume they
mean EEPROM. Date code is 2001 and that is also when we had that pellet stove
installed.

Can these things develop loss of flash memory (bit rot) this soon, after only
two decades? Any remedy short or reprogramming or is it toast?

I\'d look for other solutions before considering bit rot.

Obviously the connectors and switches need to be examined
and possibly IPA or DeOxit applied.

Electrolytic capacitors are the next failure point. Sometimes
they are obviously \"distressed\", sometimes subtly faulty.

Check the PSU rails for voltage and transients, of course.

I had an SMPS where something would:
- take a minute to start
- turn off then on, immediately start
- turn off for an hour then on, 50s to start
- turn off for 12 hours then on, 60s to start
Debugging that was one /good/ use case for a DSO.

Turned out to be a dicky electrolytic fed by a high
value resistor; it was almost as if the capacitor
was so \"dry\" had to reform the barrier before it
would work.

 

[Sylvia Else]

On 12-Dec-21 9:36 pm, Jasen Betts wrote:

On 2021-12-12, Sylvia Else <sylvia@email.invalid> wrote:
On 12-Dec-21 11:14 am, Jeff Liebermann wrote:
On Sat, 11 Dec 2021 11:51:11 -0800, Joerg <news@analogconsultants.com
wrote:

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

MTP-ROM is suppose to be good for up to 1 million write cycles:
https://anysilicon.com/semipedia/multi-time-programmable-mtp-memory-ip/
However, after only 1,000 erase/write cycles, the erase/write voltages
begins to change. See Fig 15:
https://onlinelibrary.wiley.com/doi/full/10.4218/etrij.15.0114.1428
\"After 1,000 erasing/writing cycles at a program
voltage of ±6 V with a write time of 5 ms, the
VT of a programmed cell is lowered from 2.92 V
to 2.9 V and the VT of an erased cell is raised
from -1.3 V to -0.5 V.\"
If the MTP-ROM device initially worked properly, and then slowly
started failing to recognize button pushes, that might be the problem.
Assuming you run the pellet burner for half the year and turn it
on/off once per day, that would be:
180 days * 1 cycle/day * 20 years = 3,600 erase/write cycles
which might be sufficient to see the problem.

Note: I don\'t have any experience with the Winbond W78E52BF-24.
Therefore, I don\'t know if it has this problem.


It doesn\'t seem likely that the system is writing its flash every time
it is turned on, or off. Indeed, it doesn\'t sound like it has a reason
to write its flash at all, with flash being used merely because it was
cheaper than getting a custom ROM.

Sylvia

It could be storing thermostat settings in eeprom, but that seems
unrelated to the fault reported.

Even where the device stores some information, I would expect it to do
so only when the information changes.

if it doesn\'t like the heat the fault is probably some heat sensitive part,
an electrolytic capacitor for example.

I\'m inclined to agree that that\'s more likely.

Sylvia.

 

[John Walliker]

On Sunday, 12 December 2021 at 09:38:30 UTC, Michael Schwingen wrote:

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?
Quite probably yes - I remember a series of TFT monitors some years ago
where that happened to the on-board controller. Raising/lowering VCC may
help a bit (if it is not read-protected, you might try to read the memory at
different VCC levels and see if you can get correct data, and then
re-program).

My HP vector network analyzer developed \"bit rot\" when it was around 25 years
old. One bit in one of the many uv-erasable eproms changed state. I found
it by varying the supply voltage and looking for the first bit to change. I
programmed a new eprom with the edited data and it has been working fine
ever since.
John

 

[Johann Klammer]

On 12/11/2021 09:44 PM, Joerg wrote:

On 12/11/21 12:30 PM, Rick C wrote:
On Saturday, December 11, 2021 at 2:58:14 PM UTC-5, Martin Rid wrote:
Joerg <ne...@analogconsultants.com> Wrote in message:r
Just repaired our fridge when, according to Murphy\'s law, the next appliance became shaky. Our pellet stove has twice refused to be turned off. Unfortunately, instead of analog it\'s all buttons that are operated via port pins of a micro controller. Pressing several of those willy-nilly made the on/off button work, at least long enough to turn it off. When the circuit board is cold the botton always works but not when warm after running the stove overnight.The micro controller is a Winbond W78E52BF-24 running on a 12MHz crystal. It is based on what they call electrically erasable MTP-ROM with which I assume they mean EEPROM. Date code is 2001 and that is also when we had that pellet stove installed.Can these things develop loss of flash memory (bit rot) this soon, after only two decades? Any remedy short or reprogramming or is it toast?-- Regards, Joerghttp://www.analogconsultants.com/

--
Probably a bad switch or solder connection from thermal cycling.


I don\'t think so because several other buttons also fail when warm and they aren\'t set in a matrix. The solder job on the board looks very good and it all ohms out well.


+1`

Don\'t know why the EEPROM would be suspect first. Wouldn\'t that produce a more permanent glitch? I suppose it could become temperature sensitive.


That\'s why I am asking, to see whether this is a sign of impending \"permanent\" bit rot. I don\'t know much abou this EEPROM business.


... Maybe the stove manufacturer has a note on this issue or even a recall.


I doubt they really care about that. There was another issue with this stove right after installation. I really had to rock the boat until they admitted it and actually sent out a correction note to installers with my mod in there (exhaust temp sensor).

Worst case I may have to \"analogize\" the whole enchilada but that would require a lot of reverse engineering and work. Of course, then it would last forever.

The capacitors can also silently go short.
can be temperature dependent.

 

[Hul Tytus]

In the 60\'s & 70\'s 20 years was mentioned as a life span for diffused
silicon. Somebody\'s diffusion rate.

Hul

Joerg <news@analogconsultants.com> wrote:

Just repaired our fridge when, according to Murphy\'s law, the next
appliance became shaky. Our pellet stove has twice refused to be turned
off. Unfortunately, instead of analog it\'s all buttons that are operated
via port pins of a micro controller. Pressing several of those
willy-nilly made the on/off button work, at least long enough to turn it
off. When the circuit board is cold the botton always works but not when
warm after running the stove overnight.

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Wond]

On Sat, 11 Dec 2021 11:51:11 -0800, Joerg wrote:

Just repaired our fridge when, according to Murphy\'s law, the next
appliance became shaky. Our pellet stove has twice refused to be turned
off. Unfortunately, instead of analog it\'s all buttons that are operated
via port pins of a micro controller. Pressing several of those
willy-nilly made the on/off button work, at least long enough to turn it
off. When the circuit board is cold the botton always works but not when
warm after running the stove overnight.

The micro controller is a Winbond W78E52BF-24 running on a 12MHz
crystal. It is based on what they call electrically erasable MTP-ROM
with which I assume they mean EEPROM. Date code is 2001 and that is also
when we had that pellet stove installed.

Can these things develop loss of flash memory (bit rot) this soon, after
only two decades? Any remedy short or reprogramming or is it toast?

OTOH adding wood to the stove is a pleasant chore, even in the middle
of the night.

 

[Martin Brown]

On 12/12/2021 16:02, Hul Tytus wrote:

In the 60\'s & 70\'s 20 years was mentioned as a life span for diffused
silicon. Somebody\'s diffusion rate.

Diffusion rate is *very* temperature dependent. I can\'t see a small
microcontroller at a modest clock rate running particularly hot.

--
Regards,
Martin Brown

 

[Don Y]

On 12/11/2021 12:51 PM, Joerg wrote:

Just repaired our fridge when, according to Murphy\'s law, the next appliance
became shaky. Our pellet stove has twice refused to be turned off.
Unfortunately, instead of analog it\'s all buttons that are operated via port
pins of a micro controller. Pressing several of those willy-nilly made the
on/off button work, at least long enough to turn it off. When the circuit board
is cold the botton always works but not when warm after running the stove
overnight.

The micro controller is a Winbond W78E52BF-24 running on a 12MHz crystal. It is
based on what they call electrically erasable MTP-ROM with which I assume they
mean EEPROM. Date code is 2001 and that is also when we had that pellet stove
installed.

Can these things develop loss of flash memory (bit rot) this soon, after only
two decades? Any remedy short or reprogramming or is it toast?

More likely something analog -- power supply sag/spikes, bad caps, a
floating configuration pin, etc.

Can you verify that the processor is actually *running* when it \"misbehaves\"?
(i.e., activity on ANY pins?)