Forums

EETS4K EPROT Register

Started by Adrian Vos December 8, 2003
Hi All,

I am playing with the EETS4K module on a DP256. I am using this memory space
to hold configurable data that can be altered by serial connected PC
software. I find that this memory occasionally gets erased on power up or
shutdown, and I think it could be due to not using a reset chip. I was
thinking about working around this problem by setting the protection
register for this memory to protect the EEPROM when I am not programming it,
but I cannot see that this can be done. From the documentation, the
protection can be enabled when in the disabled state, but there is no way to
diable the protection from the enabled state in my code. The actual state of
the regeister is located from one byte of the EEPROM on a reset, and I
currently set this to unprotected. I can then protect by whriting to the
EPROT register, but once protected, the only way to unprotect it is to
reset. Am I understanding this correctly? Is there any workaround? I can
understand the need to make it difficult to unprotect the EEPROM, but is
there any way to use this feature to prevent erasure of the EETS4K due to no
use of a reset chip?

Cheers,

Adrian



Adrian,

Your design MUST incorporate a a power up/down reset device. This device must pull reset low when Vdd falls below the specified minimum operating voltage and must keep reset low until Vdd falls below 1 volt. Using the protection mechanism of the EEPROM will not prevent corruption of the EEPROM during power up/down since the logic associated with the protection mechanism (or any of the other circuitry) is not characterized to operate when Vdd is outside the specified operating levels.

Bottom line is that you will need to incorporate a power up/down reset device into your hardware design.

Regards,
Gordon

Adrian Vos wrote:

>Hi All,
>
>I am playing with the EETS4K module on a DP256. I am using this memory space
>to hold configurable data that can be altered by serial connected PC
>software. I find that this memory occasionally gets erased on power up or
>shutdown, and I think it could be due to not using a reset chip. I was
>thinking about working around this problem by setting the protection
>register for this memory to protect the EEPROM when I am not programming it,
>but I cannot see that this can be done. From the documentation, the
>protection can be enabled when in the disabled state, but there is no way to
>diable the protection from the enabled state in my code. The actual state of
>the regeister is located from one byte of the EEPROM on a reset, and I
>currently set this to unprotected. I can then protect by whriting to the
>EPROT register, but once protected, the only way to unprotect it is to
>reset. Am I understanding this correctly? Is there any workaround? I can
>understand the need to make it difficult to unprotect the EEPROM, but is
>there any way to use this feature to prevent erasure of the EETS4K due to no
>use of a reset chip?
>
>Cheers,
>
>Adrian >
>-------------------- >
>">http://docs.yahoo.com/info/terms/ >
>

--
===============================================================
Gordon Doughman Ph: 937-438-6811
Motorola Semiconductor Fax: 937-434-7457
Field Applications Engineer Pager: 800-759-8352 Pin: 1304089
Suite 175
3131 Newmark Drive
Miamisburg, OH 45342

Check out my HC12 book at:
http://www.rtcbooks.com/programming.php




Thanks Gordon,

I was hoping to find a work around using my existing PCB design, but it
looks like this is not possible. If you read the crg manual, you get the
impression delay after reset feature is enough to not require a reset chip,
but it looks like a reset chip is definately required. I know this has been
done before, but can anyone recommend a suitable reset chip that is easy to
get, compact (surface mount), and cheap. I will incorporate this on a new
revision which must now be done to the PCB.

Cheers,

Adrian

----- Original Message -----
From: "Gordon Doughman" <>
To: <>
Sent: Tuesday, December 09, 2003 2:04 AM
Subject: Re: [68HC12] EETS4K EPROT Register > Adrian,
>
> Your design MUST incorporate a a power up/down reset device. This device
must pull reset low when Vdd falls below the specified minimum operating
voltage and must keep reset low until Vdd falls below 1 volt. Using the
protection mechanism of the EEPROM will not prevent corruption of the EEPROM
during power up/down since the logic associated with the protection
mechanism (or any of the other circuitry) is not characterized to operate
when Vdd is outside the specified operating levels.
>
> Bottom line is that you will need to incorporate a power up/down reset
device into your hardware design.
>
> Regards,
> Gordon
>
> Adrian Vos wrote:
>
> >Hi All,
> >
> >I am playing with the EETS4K module on a DP256. I am using this memory
space
> >to hold configurable data that can be altered by serial connected PC
> >software. I find that this memory occasionally gets erased on power up or
> >shutdown, and I think it could be due to not using a reset chip. I was
> >thinking about working around this problem by setting the protection
> >register for this memory to protect the EEPROM when I am not programming
it,
> >but I cannot see that this can be done. From the documentation, the
> >protection can be enabled when in the disabled state, but there is no way
to
> >diable the protection from the enabled state in my code. The actual state
of
> >the regeister is located from one byte of the EEPROM on a reset, and I
> >currently set this to unprotected. I can then protect by whriting to the
> >EPROT register, but once protected, the only way to unprotect it is to
> >reset. Am I understanding this correctly? Is there any workaround? I can
> >understand the need to make it difficult to unprotect the EEPROM, but is
> >there any way to use this feature to prevent erasure of the EETS4K due to
no
> >use of a reset chip?
> >
> >Cheers,
> >
> >Adrian
> >
> >
> >
> >--------------------
> >
> >
> >
> >">http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
>
> --
> ===============================================================
> Gordon Doughman Ph: 937-438-6811
> Motorola Semiconductor Fax: 937-434-7457
> Field Applications Engineer Pager: 800-759-8352 Pin: 1304089
> Suite 175
> 3131 Newmark Drive
> Miamisburg, OH 45342
>
> Check out my HC12 book at:
> http://www.rtcbooks.com/programming.php > -------------------- >
> ">http://docs.yahoo.com/info/terms/
>





Adrian Vos wrote:

> looks like this is not possible. If you read the crg manual, you get the
> impression delay after reset feature is enough to not require a reset chip,
> but it looks like a reset chip is definately required. I know this has been

right, it's not so easy to find. In the HC12 docs it's a good idea to
look for all occurances of "runaway". In the S12 docs, I still found
no equivalent.

It would be nice to have those pitfalls mentioned more conspicuous in
the docs.

> done before, but can anyone recommend a suitable reset chip that is easy to
> get, compact (surface mount), and cheap. I will incorporate this on a new

there was a long thread 2-1/2 weeks ago (2003-11-20...2003-11-23)
about the (likely) cheapest available reset chips *809 and *803, how
to use them (using 809 with totem pole output) and where to buy (ON,
NS, Fairchild...).

Oliver
--
Oliver Betz, Muenchen


MAX6326 series. SOT23, standalone.
push-pill and open-drain output versions.
Analog Device has equivalents.
Nick

> -----Original Message-----
> From: Adrian Vos [mailto:]
> Sent: Monday, December 08, 2003 5:09 PM
> To:
> Subject: Re: [68HC12] EETS4K EPROT Register > Thanks Gordon,
>
> I was hoping to find a work around using my existing PCB
> design, but it
> looks like this is not possible. If you read the crg manual,
> you get the
> impression delay after reset feature is enough to not require
> a reset chip,
> but it looks like a reset chip is definately required. I know
> this has been
> done before, but can anyone recommend a suitable reset chip
> that is easy to
> get, compact (surface mount), and cheap. I will incorporate
> this on a new
> revision which must now be done to the PCB.
>
> Cheers,
>
> Adrian
>
> ----- Original Message -----
> From: "Gordon Doughman" <>
> To: <>
> Sent: Tuesday, December 09, 2003 2:04 AM
> Subject: Re: [68HC12] EETS4K EPROT Register > > Adrian,
> >
> > Your design MUST incorporate a a power up/down reset
> device. This device
> must pull reset low when Vdd falls below the specified
> minimum operating
> voltage and must keep reset low until Vdd falls below 1 volt.
> Using the
> protection mechanism of the EEPROM will not prevent
> corruption of the EEPROM
> during power up/down since the logic associated with the protection
> mechanism (or any of the other circuitry) is not
> characterized to operate
> when Vdd is outside the specified operating levels.
> >
> > Bottom line is that you will need to incorporate a power
> up/down reset
> device into your hardware design.
> >
> > Regards,
> > Gordon
> >
> > Adrian Vos wrote:
> >
> > >Hi All,
> > >
> > >I am playing with the EETS4K module on a DP256. I am using
> this memory
> space
> > >to hold configurable data that can be altered by serial
> connected PC
> > >software. I find that this memory occasionally gets erased
> on power up or
> > >shutdown, and I think it could be due to not using a reset
> chip. I was
> > >thinking about working around this problem by setting the
> protection
> > >register for this memory to protect the EEPROM when I am
> not programming
> it,
> > >but I cannot see that this can be done. From the documentation, the
> > >protection can be enabled when in the disabled state, but
> there is no way
> to
> > >diable the protection from the enabled state in my code.
> The actual state
> of
> > >the regeister is located from one byte of the EEPROM on a
> reset, and I
> > >currently set this to unprotected. I can then protect by
> whriting to the
> > >EPROT register, but once protected, the only way to
> unprotect it is to
> > >reset. Am I understanding this correctly? Is there any
> workaround? I can
> > >understand the need to make it difficult to unprotect the
> EEPROM, but is
> > >there any way to use this feature to prevent erasure of
> the EETS4K due to
> no
> > >use of a reset chip?
> > >
> > >Cheers,
> > >
> > >Adrian
> > >
> > >
> > >
> > >--------------------
> > >
> > >
> > >
> > >">http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> > >
> >
> > --
> > ===============================================================
> > Gordon Doughman Ph: 937-438-6811
> > Motorola Semiconductor Fax: 937-434-7457
> > Field Applications Engineer Pager: 800-759-8352 Pin: 1304089
> > Suite 175
> > 3131 Newmark Drive
> > Miamisburg, OH 45342
> >
> > Check out my HC12 book at:
> > http://www.rtcbooks.com/programming.php
> >
> >
> >
> >
> >
> > --------------------
> >
> >
> >
> > ">http://docs.yahoo.com/info/terms/
> > ------------------------ Yahoo! Groups Sponsor
> ---------------------~-->
> Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark
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> --------------------------
> -------~->
>
> -------------------- >
> ">http://docs.yahoo.com/info/terms/



Hello Adrian,

The EVB i' currently working with uses a Maxim-Dallas MAX6421 which is a very compact surface mount device and only requires one external capacitor.

Good luck!
Robert

>
>I was hoping to find a work around using my existing PCB design, but it
>looks like this is not possible. If you read the crg manual, you get the
>impression delay after reset feature is enough to not require a reset chip,
>but it looks like a reset chip is definately required. I know this has been
>done before, but can anyone recommend a suitable reset chip that is easy to
>get, compact (surface mount), and cheap. I will incorporate this on a new
>revision which must now be done to the PCB.
>
>Cheers,
>
>Adrian


Check www.maxim-ic.com <www.maxim-ic.com> for the supervisory ccts.

The one we use with the dg128a is the MAX6402BS31, I don't have the BOM
here, but I think we were using the bump package. I would not recommend that
unless you are really tight on board space. We are going to switch to
another package, its really intended for cell phones so I am told.

Somethings to watch for are,
* the reset level you want to trigger at,
* push pull configuration,
* whether you want a switch input to the cct,
* or just a voltage level triggered reset,
* and the package configuration.

The pricing is on the web site, and you can order samples without charge.
The support has been good for us.

Bob Lewis


Gordon,

I assume this only applies to parts without the on on chip low
voltage reset. I am using a E128 chip, and am relying on the onboard
low voltage reset. Is this OK?

I also assume the FLASH can be corrupted as well as the EEPROM (not
that the the E128 as EEPROM).

David --- In , Gordon Doughman <g.doughman@m...>
wrote:
> Adrian,
>
> Your design MUST incorporate a a power up/down reset device. This
device must pull reset low when Vdd falls below the specified minimum
operating voltage and must keep reset low until Vdd falls below 1
volt. Using the protection mechanism of the EEPROM will not prevent
corruption of the EEPROM during power up/down since the logic
associated with the protection mechanism (or any of the other
circuitry) is not characterized to operate when Vdd is outside the
specified operating levels.
>
> Bottom line is that you will need to incorporate a power up/down
reset device into your hardware design.
>
> Regards,
> Gordon
>
> Adrian Vos wrote:
>
> >Hi All,
> >
> >I am playing with the EETS4K module on a DP256. I am using this
memory space
> >to hold configurable data that can be altered by serial connected
PC
> >software. I find that this memory occasionally gets erased on
power up or
> >shutdown, and I think it could be due to not using a reset chip. I
was
> >thinking about working around this problem by setting the
protection
> >register for this memory to protect the EEPROM when I am not
programming it,
> >but I cannot see that this can be done. From the documentation, the
> >protection can be enabled when in the disabled state, but there is
no way to
> >diable the protection from the enabled state in my code. The
actual state of
> >the regeister is located from one byte of the EEPROM on a reset,
and I
> >currently set this to unprotected. I can then protect by whriting
to the
> >EPROT register, but once protected, the only way to unprotect it
is to
> >reset. Am I understanding this correctly? Is there any workaround?
I can
> >understand the need to make it difficult to unprotect the EEPROM,
but is
> >there any way to use this feature to prevent erasure of the EETS4K
due to no
> >use of a reset chip?
> >
> >Cheers,
> >
> >Adrian
> >
> >
> >
> >--------------------
> >
> >
> >
> >">http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
>
> --
> ===============================================================
> Gordon Doughman Ph: 937-438-6811
> Motorola Semiconductor Fax: 937-434-7457
> Field Applications Engineer Pager: 800-759-8352 Pin: 1304089
> Suite 175
> 3131 Newmark Drive
> Miamisburg, OH 45342
>
> Check out my HC12 book at:
> http://www.rtcbooks.com/programming.php




David,

Correct on both counts. Only devices NOT having the on-chip low voltage
reset must incorporate an external LVI reset device.

Regards,
Gordon

djsimpson100 wrote:

>Gordon,
>
>I assume this only applies to parts without the on on chip low
>voltage reset. I am using a E128 chip, and am relying on the onboard
>low voltage reset. Is this OK?
>
>I also assume the FLASH can be corrupted as well as the EEPROM (not
>that the the E128 as EEPROM).
>
>David >--- In , Gordon Doughman <g.doughman@m...> wrote:
>
>>Adrian,
>>
>>Your design MUST incorporate a a power up/down reset device. This
>>
>device must pull reset low when Vdd falls below the specified minimum
>operating voltage and must keep reset low until Vdd falls below 1
>volt. Using the protection mechanism of the EEPROM will not prevent
>corruption of the EEPROM during power up/down since the logic
>associated with the protection mechanism (or any of the other
>circuitry) is not characterized to operate when Vdd is outside the
>specified operating levels.
>
>>Bottom line is that you will need to incorporate a power up/down
>>
>reset device into your hardware design.
>
>>Regards,
>>Gordon
>>
>>Adrian Vos wrote:
>>
>>
>>>Hi All,
>>>
>>>I am playing with the EETS4K module on a DP256. I am using this
>>>
>memory space
>
>>>to hold configurable data that can be altered by serial connected
>>>
>PC
>
>>>software. I find that this memory occasionally gets erased on
>>>
>power up or
>
>>>shutdown, and I think it could be due to not using a reset chip. I
>>>
>was
>
>>>thinking about working around this problem by setting the
>>>
>protection
>
>>>register for this memory to protect the EEPROM when I am not
>>>
>programming it,
>
>>>but I cannot see that this can be done. From the documentation, the
>>>protection can be enabled when in the disabled state, but there is
>>>
>no way to
>
>>>diable the protection from the enabled state in my code. The
>>>
>actual state of
>
>>>the regeister is located from one byte of the EEPROM on a reset,
>>>
>and I
>
>>>currently set this to unprotected. I can then protect by whriting
>>>
>to the
>
>>>EPROT register, but once protected, the only way to unprotect it
>>>
>is to
>
>>>reset. Am I understanding this correctly? Is there any workaround?
>>>
>I can
>
>>>understand the need to make it difficult to unprotect the EEPROM,
>>>
>but is
>
>>>there any way to use this feature to prevent erasure of the EETS4K
>>>
>due to no
>
>>>use of a reset chip?
>>>
>>>Cheers,
>>>
>>>Adrian
>>>
>>>
>>>
>>>--------------------
>>>
>>>
>>>
>>>">http://docs.yahoo.com/info/terms/
>
>>>
>>>
>>>
>>--
>>===============================================================
>>Gordon Doughman Ph: 937-438-6811
>>Motorola Semiconductor Fax: 937-434-7457
>>Field Applications Engineer Pager: 800-759-8352 Pin: 1304089
>>Suite 175
>>3131 Newmark Drive
>>Miamisburg, OH 45342
>>
>>Check out my HC12 book at:
>>http://www.rtcbooks.com/programming.php
> >
>-------------------- >
>">http://docs.yahoo.com/info/terms/ >

--
===============================================================
Gordon Doughman Ph: 937-438-6811
Motorola Semiconductor Fax: 937-434-7457
Field Applications Engineer Pager: 800-759-8352 Pin: 1304089
Suite 175
3131 Newmark Drive
Miamisburg, OH 45342

Check out my HC12 book at:
http://www.rtcbooks.com/programming.php



Is there any device feature summary for S12 which I can use to check which
versions have low voltage reset. I am only using the DP256 as it was the all
feature encompassing version when I started this project, but there may be
other versions of S12 that may have everythin I need including the low
voltage rest. Does motorla have some table with device vs features to find
other devices compatible with my requirements?

Thanks,

Adrian

----- Original Message -----
From: "Gordon Doughman" <>
To: <>
Sent: Friday, December 12, 2003 3:31 AM
Subject: Re: [68HC12] Re: EETS4K EPROT Register > David,
>
> Correct on both counts. Only devices NOT having the on-chip low voltage
> reset must incorporate an external LVI reset device.
>
> Regards,
> Gordon
>
> djsimpson100 wrote:
>
> >Gordon,
> >
> >I assume this only applies to parts without the on on chip low
> >voltage reset. I am using a E128 chip, and am relying on the onboard
> >low voltage reset. Is this OK?
> >
> >I also assume the FLASH can be corrupted as well as the EEPROM (not
> >that the the E128 as EEPROM).
> >
> >David
> >
> >
> >--- In , Gordon Doughman <g.doughman@m...> wrote:
> >
> >>Adrian,
> >>
> >>Your design MUST incorporate a a power up/down reset device. This
> >>
> >device must pull reset low when Vdd falls below the specified minimum
> >operating voltage and must keep reset low until Vdd falls below 1
> >volt. Using the protection mechanism of the EEPROM will not prevent
> >corruption of the EEPROM during power up/down since the logic
> >associated with the protection mechanism (or any of the other
> >circuitry) is not characterized to operate when Vdd is outside the
> >specified operating levels.
> >
> >>Bottom line is that you will need to incorporate a power up/down
> >>
> >reset device into your hardware design.
> >
> >>Regards,
> >>Gordon
> >>
> >>Adrian Vos wrote:
> >>
> >>
> >>>Hi All,
> >>>
> >>>I am playing with the EETS4K module on a DP256. I am using this
> >>>
> >memory space
> >
> >>>to hold configurable data that can be altered by serial connected
> >>>
> >PC
> >
> >>>software. I find that this memory occasionally gets erased on
> >>>
> >power up or
> >
> >>>shutdown, and I think it could be due to not using a reset chip. I
> >>>
> >was
> >
> >>>thinking about working around this problem by setting the
> >>>
> >protection
> >
> >>>register for this memory to protect the EEPROM when I am not
> >>>
> >programming it,
> >
> >>>but I cannot see that this can be done. From the documentation, the
> >>>protection can be enabled when in the disabled state, but there is
> >>>
> >no way to
> >
> >>>diable the protection from the enabled state in my code. The
> >>>
> >actual state of
> >
> >>>the regeister is located from one byte of the EEPROM on a reset,
> >>>
> >and I
> >
> >>>currently set this to unprotected. I can then protect by whriting
> >>>
> >to the
> >
> >>>EPROT register, but once protected, the only way to unprotect it
> >>>
> >is to
> >
> >>>reset. Am I understanding this correctly? Is there any workaround?
> >>>
> >I can
> >
> >>>understand the need to make it difficult to unprotect the EEPROM,
> >>>
> >but is
> >
> >>>there any way to use this feature to prevent erasure of the EETS4K
> >>>
> >due to no
> >
> >>>use of a reset chip?
> >>>
> >>>Cheers,
> >>>
> >>>Adrian
> >>>
> >>>
> >>>
> >>>--------------------
> >>>
> >>>
> >>>
> >>>">http://docs.yahoo.com/info/terms/
> >
> >>>
> >>>
> >>>
> >>--
> >>===============================================================
> >>Gordon Doughman Ph: 937-438-6811
> >>Motorola Semiconductor Fax: 937-434-7457
> >>Field Applications Engineer Pager: 800-759-8352 Pin: 1304089
> >>Suite 175
> >>3131 Newmark Drive
> >>Miamisburg, OH 45342
> >>
> >>Check out my HC12 book at:
> >>http://www.rtcbooks.com/programming.php
> >>
> >
> >
> >
> >--------------------
> >
> >
> >
> >">http://docs.yahoo.com/info/terms/
> >
> >
> >
>
> --
> ===============================================================
> Gordon Doughman Ph: 937-438-6811
> Motorola Semiconductor Fax: 937-434-7457
> Field Applications Engineer Pager: 800-759-8352 Pin: 1304089
> Suite 175
> 3131 Newmark Drive
> Miamisburg, OH 45342
>
> Check out my HC12 book at:
> http://www.rtcbooks.com/programming.php > -------------------- >
> ">http://docs.yahoo.com/info/terms/
>