Intel and using pins for multiple purposes

[Sylvia Else]

I was wondering why I couldn't use the watchdog timer function on one of
my computers - the driver says that it's been disabled in hardware.

A look at the chipset page reveals that when the system is powered up, a
pin is sampled, and if it is high, the watchdog timer function is indeed
disabled.

The pin has a pulldown resistor, which the spec warns can be as high as 50K.

Only thing is, the rest of the time, the pin is the output intended to
drive (indirectly) the computer speaker.

So if the speaker driver circuitry is implemented in a way that could
behave as a modest pullup, it could unintentionally disable the watchdog
timer function. I rather suspect that this is what is happening, since I
can't see any reason for a MB manufacturer to deliberately disable such
an obscure function.

Which leaves two questions.

1) Was the speaker output pin really the best choice for this?

2) Where is the need to disable the watchdog timer function at all? If a
system doesn't program it to operate, then it won't. There seems no
earthly need to make it impossible for software to use it. It's not even
the kind of thing that would make for product differentiation (charge
more for a board without the functionality disabled).

Interested readers can find the spec here:

<http://www.intel.com/content/dam/doc/datasheet/6-chipset-c200-chipset-datasheet.pdf>

Search for "No Reboot (NR)" without the quotes.

Grrrrr!

Sylvia.

 

[yaputya]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba56laFh8muU1@mid.individual.net...

I was wondering why I couldn't use the watchdog timer function on one of my computers - the driver says that it's been disabled in
hardware.

What do you need the watchdog for?

A look at the chipset page reveals that when the system is powered up, a pin is sampled, and if it is high, the watchdog timer
function is indeed disabled.

The pin has a pulldown resistor, which the spec warns can be as high as 50K.

Only thing is, the rest of the time, the pin is the output intended to drive (indirectly) the computer speaker.

So if the speaker driver circuitry is implemented in a way that could behave as a modest pullup, it could unintentionally disable
the watchdog timer function. I rather suspect that this is what is happening, since I can't see any reason for a MB manufacturer
to deliberately disable such an obscure function.

Which leaves two questions.

1) Was the speaker output pin really the best choice for this?

2) Where is the need to disable the watchdog timer function at all? If a system doesn't program it to operate, then it won't.
There seems no earthly need to make it impossible for software to use it. It's not even the kind of thing that would make for
product differentiation (charge more for a board without the functionality disabled).

Interested readers can find the spec here:

http://www.intel.com/content/dam/doc/datasheet/6-chipset-c200-chipset-datasheet.pdf

Search for "No Reboot (NR)" without the quotes.

Grrrrr!

Sylvia.

 

[Sylvia Else]

On 22/09/2013 7:57 PM, yaputya wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one of my computers - the driver says that it's been disabled in
hardware.

What do you need the watchdog for?

Restart the system if it hangs.

Sylvia.

 

[Bob Milutinovic]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:ba56laFh8muU1@mid.individual.net...

I was wondering why I couldn't use the watchdog timer function on one of my
computers - the driver says that it's been disabled in hardware.

A look at the chipset page reveals that when the system is powered up, a
pin is sampled, and if it is high, the watchdog timer function is indeed
disabled.

The pin has a pulldown resistor, which the spec warns can be as high as
50K.

Only thing is, the rest of the time, the pin is the output intended to
drive (indirectly) the computer speaker.

So if the speaker driver circuitry is implemented in a way that could
behave as a modest pullup, it could unintentionally disable the watchdog
timer function. I rather suspect that this is what is happening, since I
can't see any reason for a MB manufacturer to deliberately disable such an
obscure function.

Which leaves two questions.

1) Was the speaker output pin really the best choice for this?

2) Where is the need to disable the watchdog timer function at all? If a
system doesn't program it to operate, then it won't. There seems no
earthly need to make it impossible for software to use it. It's not even
the kind of thing that would make for product differentiation (charge more
for a board without the functionality disabled).

Interested readers can find the spec here:

http://www.intel.com/content/dam/doc/datasheet/6-chipset-c200-chipset-datasheet.pdf

Search for "No Reboot (NR)" without the quotes.

Grrrrr!

Sylvia.

I can only imagine that Intel provided a method for disabling the hardware
watchdog in order to avoid an infinite boot loop in the event that the timer
was set to too short a duration.

I haven't looked into the architecture, but the speaker output would likely
be the least critical pin (system function wise), and would tie in well with
the "system diagnostics" side of things - the motherboard manufacturer
definitely seems to have botched it.

If you have a decent (i.e., very high impedance) multimeter, check the
voltage on that pin at boot time. A decent DSO would be even better, but I
suspect it's a simple resistive pull up to +Vcc rather than a pulse in
response to something else.

If it is indeed pulling it up, simply cut the speaker circuit off - I'd
suspect in your scenario watchdog time functionality would be more
beneficial than the provision of a power-on beep. If you still want
provision for power-on diagnostics, put a switch in there, to switch the
speaker circuit back in if the system fails.

--
Bob Milutinovic
Cognicom

 

[yaputya]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba870hF5thbU1@mid.individual.net...

On 22/09/2013 7:57 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one of my computers - the driver says that it's been disabled
in
hardware.

What do you need the watchdog for?

Restart the system if it hangs.

Sylvia.

Yeah but why do you need it running unattended?
If it hangs you must have a software/hardware problem.
You shouldn't be using a Windoze PC for anything critical anyway.

 

[Bob Milutinovic]

"yaputya" <yaputya.leftlegin@gmail.com> wrote in message
news:ba8ff5F7mk6U1@mid.individual.net...

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:ba870hF5thbU1@mid.individual.net...
On 22/09/2013 7:57 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one
of my computers - the driver says that it's been disabled
in
hardware.

What do you need the watchdog for?

Restart the system if it hangs.

Sylvia.

Yeah but why do you need it running unattended?
If it hangs you must have a software/hardware problem.

It could also be something as simple as a flipped bit pursuant to a
voltage/magnetic surge. There's a reason why 100% of dedicated servers
actually have a functional watchdog implementation.

> You shouldn't be using a Windoze PC for anything critical anyway.

I didn't see anywhere in her post that she'd written she was using Windows.

Just for the record though, I have a server sitting here which has been
running Windows (2K Server) continuously since late 2002 and hasn't once
crashed due to software failure (I'll admit that it's had two PSUs and one
HDD replaced in that time - but neither of these have anything to do with
choice of operating system). I also have a Debian machine which falls over
of its own accord at least once a week due to memory leaks in a driver.

--
Bob Milutinovic
Cognicom

 

[Sylvia Else]

On 23/09/2013 1:08 AM, yaputya wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba870hF5thbU1@mid.individual.net...
On 22/09/2013 7:57 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one of my computers - the driver says that it's been disabled
in
hardware.

What do you need the watchdog for?

Restart the system if it hangs.

Sylvia.

Yeah but why do you need it running unattended?
If it hangs you must have a software/hardware problem.
You shouldn't be using a Windoze PC for anything critical anyway.

Who said it was Windows?

I say I want to use the watchdog timer. I can't for the life of me see
how you can conclude that I shouldn't want to.

Sylvia.

 

[Sylvia Else]

On 23/09/2013 12:12 AM, Bob Milutinovic wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one
of my computers - the driver says that it's been disabled in hardware.

A look at the chipset page reveals that when the system is powered up,
a pin is sampled, and if it is high, the watchdog timer function is
indeed disabled.

The pin has a pulldown resistor, which the spec warns can be as high
as 50K.

Only thing is, the rest of the time, the pin is the output intended to
drive (indirectly) the computer speaker.

So if the speaker driver circuitry is implemented in a way that could
behave as a modest pullup, it could unintentionally disable the
watchdog timer function. I rather suspect that this is what is
happening, since I can't see any reason for a MB manufacturer to
deliberately disable such an obscure function.

Which leaves two questions.

1) Was the speaker output pin really the best choice for this?

2) Where is the need to disable the watchdog timer function at all? If
a system doesn't program it to operate, then it won't. There seems no
earthly need to make it impossible for software to use it. It's not
even the kind of thing that would make for product differentiation
(charge more for a board without the functionality disabled).

Interested readers can find the spec here:

http://www.intel.com/content/dam/doc/datasheet/6-chipset-c200-chipset-datasheet.pdf


Search for "No Reboot (NR)" without the quotes.

Grrrrr!

Sylvia.


I can only imagine that Intel provided a method for disabling the
hardware watchdog in order to avoid an infinite boot loop in the event
that the timer was set to too short a duration.

Though the only thing that could stuff things up that badly would be the
BIOS, and if a BIOS developer gets things that wrong on a system with a
BIOS rom that's soldered into place, and thereby not reflashable, they
strongly deserve to have to buy a new motherboard.

I haven't looked into the architecture, but the speaker output would
likely be the least critical pin (system function wise), and would tie
in well with the "system diagnostics" side of things - the motherboard
manufacturer definitely seems to have botched it.

After posting, I did reflect on it some more, and it certainly seems
that the most obvious speaker driver implementation (and we're not
talking Hi-Fi here), is not likely to function as a pull-up. I've
entered a support ticket with the board manufacturer - but what are the
odds that they'll just tell me to reflash to the most recent BIOS? I
already did anyway, before looking at the hardware details. It didn't
help, of course.

If you have a decent (i.e., very high impedance) multimeter, check the
voltage on that pin at boot time. A decent DSO would be even better, but
I suspect it's a simple resistive pull up to +Vcc rather than a pulse in
response to something else.

Unfortunately, I can't even reach the pin - it's a surface mounted
device soldered to the board with an array of pins. I've tried
backtracking from the loudspeaker driver (using a magnifying glass), but
I quickly get lost, and I suspect this is a multi-layer board. Buying an
X-ray machine to diagnose this seems a bit over-the-top.

If it is indeed pulling it up, simply cut the speaker circuit off - I'd
suspect in your scenario watchdog time functionality would be more
beneficial than the provision of a power-on beep. If you still want
provision for power-on diagnostics, put a switch in there, to switch the
speaker circuit back in if the system fails.

If necessary, I'll just buy a third-party watchdog card.

Sylvia.

 

[yaputya]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba9hu8FeokrU1@mid.individual.net...

On 23/09/2013 1:08 AM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba870hF5thbU1@mid.individual.net...
On 22/09/2013 7:57 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one of my computers - the driver says that it's been
disabled
in
hardware.

What do you need the watchdog for?

Restart the system if it hangs.

Sylvia.

Yeah but why do you need it running unattended?
If it hangs you must have a software/hardware problem.
You shouldn't be using a Windoze PC for anything critical anyway.


Who said it was Windows?

I assumed so, around 90% of PCs use it.

I say I want to use the watchdog timer. I can't for the life of me see how you can conclude that I shouldn't want to.

You normally only use a watchdog to reboot when a problem occurs.
If you are having PC problems this ng might be able to help you fix them directly.
So, why do you need a watchdog in the first place?

Sylvia.

 

[Sylvia Else]

On 23/09/2013 4:04 PM, yaputya wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba9hu8FeokrU1@mid.individual.net...
On 23/09/2013 1:08 AM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba870hF5thbU1@mid.individual.net...
On 22/09/2013 7:57 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one of my computers - the driver says that it's been
disabled
in
hardware.

What do you need the watchdog for?

Restart the system if it hangs.

Sylvia.

Yeah but why do you need it running unattended?
If it hangs you must have a software/hardware problem.
You shouldn't be using a Windoze PC for anything critical anyway.


Who said it was Windows?

I assumed so, around 90% of PCs use it.

So you assumed that I was doing something critical, but that I was using
Windows for it, despite, in your view, the inappropriateness of that.
Seems a bit arrogant to me.

I say I want to use the watchdog timer. I can't for the life of me see how you can conclude that I shouldn't want to.

You normally only use a watchdog to reboot when a problem occurs.
If you are having PC problems this ng might be able to help you fix them directly.
So, why do you need a watchdog in the first place?

I can't fix a problem until it exists, and if one arises, then without
the watchdog timer, the system will hang until such time as I notice,
which I don't want.

Pretty much the standard use of watchdog timer, indeed.

Sylvia.

 

[yaputya]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:baa588Fi8lmU1@mid.individual.net...

On 23/09/2013 4:04 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba9hu8FeokrU1@mid.individual.net...
On 23/09/2013 1:08 AM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba870hF5thbU1@mid.individual.net...
On 22/09/2013 7:57 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one of my computers - the driver says that it's been
disabled
in
hardware.

What do you need the watchdog for?

Restart the system if it hangs.

Sylvia.

Yeah but why do you need it running unattended?
If it hangs you must have a software/hardware problem.
You shouldn't be using a Windoze PC for anything critical anyway.


Who said it was Windows?

I assumed so, around 90% of PCs use it.

So you assumed that I was doing something critical, but that I was using Windows for it, despite, in your view, the
inappropriateness of that. Seems a bit arrogant to me.

Not really, and no offence intended.
I simply meant *if* it was critical, you shouldn't depend on Windows.
Since you haven't given a reason why you want to go to the trouble of using
a watchdog, I still don't know if your application is critical or not.
If you are using Windows, just say so.

I say I want to use the watchdog timer. I can't for the life of me see how you can conclude that I shouldn't want to.

You normally only use a watchdog to reboot when a problem occurs.
If you are having PC problems this ng might be able to help you fix them directly.
So, why do you need a watchdog in the first place?

I can't fix a problem until it exists, and if one arises, then without the watchdog timer, the system will hang until such time as
I notice, which I don't want.

A watchdog reset won't fix hardware software problems.
And if you aren't around to notice a crash, you won't be around to see the watchdog stuck
in an endless reboot sequence either, if the fault is still present. Unless you write recovery
code your PC will not resume where it left off either.

Pretty much the standard use of watchdog timer, indeed.

You still haven't explained what you are doing with the PC that justifies
a watchdog. You may be better off with a more stable O/S instead.

Sylvia.

 

[Sylvia Else]

On 23/09/2013 5:14 PM, yaputya wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:baa588Fi8lmU1@mid.individual.net...
On 23/09/2013 4:04 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba9hu8FeokrU1@mid.individual.net...
On 23/09/2013 1:08 AM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba870hF5thbU1@mid.individual.net...
On 22/09/2013 7:57 PM, yaputya wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message news:ba56laFh8muU1@mid.individual.net...
I was wondering why I couldn't use the watchdog timer function on one of my computers - the driver says that it's been
disabled
in
hardware.

What do you need the watchdog for?

Restart the system if it hangs.

Sylvia.

Yeah but why do you need it running unattended?
If it hangs you must have a software/hardware problem.
You shouldn't be using a Windoze PC for anything critical anyway.


Who said it was Windows?

I assumed so, around 90% of PCs use it.

So you assumed that I was doing something critical, but that I was using Windows for it, despite, in your view, the
inappropriateness of that. Seems a bit arrogant to me.

Not really, and no offence intended.
I simply meant *if* it was critical, you shouldn't depend on Windows.
Since you haven't given a reason why you want to go to the trouble of using
a watchdog, I still don't know if your application is critical or not.
If you are using Windows, just say so.


I say I want to use the watchdog timer. I can't for the life of me see how you can conclude that I shouldn't want to.

You normally only use a watchdog to reboot when a problem occurs.
If you are having PC problems this ng might be able to help you fix them directly.
So, why do you need a watchdog in the first place?

I can't fix a problem until it exists, and if one arises, then without the watchdog timer, the system will hang until such time as
I notice, which I don't want.

A watchdog reset won't fix hardware software problems.
And if you aren't around to notice a crash, you won't be around to see the watchdog stuck
in an endless reboot sequence either, if the fault is still present. Unless you write recovery
code your PC will not resume where it left off either.

It already resumes its critical task on a reboot.

Pretty much the standard use of watchdog timer, indeed.

You still haven't explained what you are doing with the PC that justifies
a watchdog. You may be better off with a more stable O/S instead.

Remind me why it needs to be justified.

Sylvia.

 

[Sylvia Else]

On 21/09/2013 7:19 PM, Sylvia Else wrote:

I was wondering why I couldn't use the watchdog timer function on one of
my computers - the driver says that it's been disabled in hardware.

A look at the chipset page reveals that when the system is powered up, a
pin is sampled, and if it is high, the watchdog timer function is indeed
disabled.

The pin has a pulldown resistor, which the spec warns can be as high as
50K.

Only thing is, the rest of the time, the pin is the output intended to
drive (indirectly) the computer speaker.

So if the speaker driver circuitry is implemented in a way that could
behave as a modest pullup, it could unintentionally disable the watchdog
timer function. I rather suspect that this is what is happening, since I
can't see any reason for a MB manufacturer to deliberately disable such
an obscure function.

Which leaves two questions.

1) Was the speaker output pin really the best choice for this?

2) Where is the need to disable the watchdog timer function at all? If a
system doesn't program it to operate, then it won't. There seems no
earthly need to make it impossible for software to use it. It's not even
the kind of thing that would make for product differentiation (charge
more for a board without the functionality disabled).

Interested readers can find the spec here:

http://www.intel.com/content/dam/doc/datasheet/6-chipset-c200-chipset-datasheet.pdf


Search for "No Reboot (NR)" without the quotes.

Grrrrr!

Sylvia.

I submitted a support ticket to the board manufacturer, whose initial
response was that they don't support Linux, and that I should install a
Windows operating system and try it there.

I said I'be be willing to try, but that as far I can see there's no
official driver for the hardware.

Their response is now that I contact Microsort for further information.

Perhaps they mean that if I get enough information from Microsoft to
write a driver for the hardare, do so, and then it doesn't work, they'll
take the matter seriously.

The real situation seems to be that they don't support any chipset
feature that Windows doesn't use, and it's pot-luck whether it'll work.

The board, BTW, is a GA-H61M-S2PV (rev 2.0). I've also tried a revision
2.2, with the same result.

Sylvia.