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Discussion Groups | 68HC12 | Re: What reset chip do you use?

Join our technical discussions about Freescale Microcontrollers: M68HC12. (Freescale Semiconductor is a Subsidiary of Motorola).

Fixed point math - Mike Turgeman - May 1 12:04:00 2003

Hi all,
I am looking for 32 bit fixed point math routines. Any help would be appreciable.
Mike

[Non-text portions of this message have been removed]




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RE: Fixed point math - Paul Johnson - May 1 12:19:00 2003

The book "Starting Forth" by Leo Brodie (if memory serves) has an excellent
section on fixed point math. Even though it is written for Forth, it is
pretty easy to map to another processor/language.

Paul

> -----Original Message-----
> From: Mike Turgeman [mailto:]
> Sent: Thursday, May 01, 2003 10:04 AM
> To:
> Subject: [68HC12] Fixed point math > Hi all,
> I am looking for 32 bit fixed point math routines. Any help would
> be appreciable.
> Mike
>
> [Non-text portions of this message have been removed] >
> --------------------------------------------------------
> To unsubscribe from this group, send an email to: > To learn more about Motorola Microcontrollers, please visit
> http://www.motorola.com/mcu






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What reset chip do you use? - Paul Johnson - May 1 13:34:00 2003

I am interested in anyone's experience with chips to control the reset line
of the HC12 family, or specifically the MC68HC912DT128A. We are beginning
to suspect that our circuitry may be culpable in corrupting flash memory.

Thanks,

Paul Johnson




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RE: What reset chip do you use? - Killingsworth, Steve - May 1 13:43:00 2003


We use the Analog Devices ADM809LART with the DG128A processor and have
never had any problems. It comes in a SOT-23 package. We have been running
the processor with this device for nearly 2 years using both crystal and
package oscillators.

Stephen Killingsworth
President, Embedded XLence, Inc.
Embedded Systems Engineering -----Original Message-----
From: Paul Johnson [mailto:]
Sent: Thursday, May 01, 2003 2:35 PM
To:
Subject: [68HC12] What reset chip do you use? I am interested in anyone's experience with chips to control the reset line
of the HC12 family, or specifically the MC68HC912DT128A. We are beginning
to suspect that our circuitry may be culpable in corrupting flash memory.

Thanks,

Paul Johnson
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Re: What reset chip do you use? - Ed Taylor - May 1 13:52:00 2003

hi:
mc34064
regards,

ed
----- Original Message -----
From: "Paul Johnson" <>
To: <>
Sent: Thursday, May 01, 2003 12:34 PM
Subject: [68HC12] What reset chip do you use? > I am interested in anyone's experience with chips to control the reset
line
> of the HC12 family, or specifically the MC68HC912DT128A. We are beginning
> to suspect that our circuitry may be culpable in corrupting flash memory.
>
> Thanks,
>
> Paul Johnson >
> --------------------------------------------------------
> To unsubscribe from this group, send an email to: > To learn more about Motorola Microcontrollers, please visit
> http://www.motorola.com/mcu





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RE: What reset chip do you use? - Jeff McKnight - May 1 14:52:00 2003

MC34164P-5 with the DG128A - no problems.

-----Original Message-----
From: Ed Taylor [mailto:]
Sent: Thursday, May 01, 2003 2:52 PM
To:
Subject: Re: [68HC12] What reset chip do you use? hi:
mc34064
regards,

ed
----- Original Message -----
From: "Paul Johnson" <>
To: <>
Sent: Thursday, May 01, 2003 12:34 PM
Subject: [68HC12] What reset chip do you use? > I am interested in anyone's experience with chips to control the reset
line
> of the HC12 family, or specifically the MC68HC912DT128A. We are beginning
> to suspect that our circuitry may be culpable in corrupting flash memory.
>
> Thanks,
>
> Paul Johnson >
> --------------------------------------------------------
> To unsubscribe from this group, send an email to: > To learn more about Motorola Microcontrollers, please visit
> http://www.motorola.com/mcu

--------------------------------------------------------
To unsubscribe from this group, send an email to: To learn more about Motorola Microcontrollers, please visit
http://www.motorola.com/mcu





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Re: Fixed point math - Oliver Betz - May 1 15:09:00 2003

Mike Turgeman wrote:

> I am looking for 32 bit fixed point math routines. Any help would be appreciable.

Good compilers (Cosmic, Hiware) have optimized math routines. AFAIR,
a long/long division takes approx. 200 cycles.

It's worth the money to buy a good compiler in many cases, the code
is not much larger or slower than hand coded and you save time.

Oliver
--
Oliver Betz, Muenchen



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Re: What reset chip do you use? - Oliver Betz - May 1 15:09:00 2003

Paul Johnson wrote:

> I am interested in anyone's experience with chips to control the reset line
> of the HC12 family, or specifically the MC68HC912DT128A. We are beginning
> to suspect that our circuitry may be culpable in corrupting flash memory.

This can (and will) be the case if your crystal oscillator starts
slower than reset is released, e.g with the mentioned 34064 and Vcc
rise time shorter than several milliseconds (BTDT).

Therefore I selected the *809 delayed power on reset since it's cheap
(sometimes even cheaper than the 34064) and available from really
many companies.

Oliver
--
Oliver Betz, Muenchen



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RE: What reset chip do you use? - Roth Markus - May 2 0:36:00 2003

After similar problems with the Flash as you described, we used the
MAX6328UR29 (SOT23-3 package). For some safety reasons we had to use a very
low switch voltage of this reset device. But they are available at higher
(normal) voltages of 4...5V in 100mV steps from Maxim (Datasheet:
http://pdfserv.maxim-ic.com/arpdf/MAX6326-MAX6348.pdf). We use the open
drain device to allow the uC to pull down the reset line.
There ain't no more Flash problems after using this device.

Markus

> -----Original Message-----
> From: Paul Johnson [mailto:]
> Sent: Thursday, May 01, 2003 2:35 PM
> To:
> Subject: [68HC12] What reset chip do you use? > I am interested in anyone's experience with chips to control
> the reset line
> of the HC12 family, or specifically the MC68HC912DT128A. We
> are beginning
> to suspect that our circuitry may be culpable in corrupting
> flash memory.
>
> Thanks,
>
> Paul Johnson >
> --------------------------------------------------------
> To unsubscribe from this group, send an email to: > To learn more about Motorola Microcontrollers, please visit
> http://www.motorola.com/mcu > This e-mail and any files transmitted with it (« Message ») are confidential
and may contain privileged information.
This Message is intended solely for the addressee(s). If you have received
this Message in error, please inform us promptly by reply e-mail then delete
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Any unauthorized use, review, retransmission, dissemination, distribution,
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prohibited.
E-mails are susceptible to alteration. Neither Technip-Coflexip nor any of
its subsidiaries and affiliates shall be liable for the Message if altered,
changed or falsified --------------------------------------------------------
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http://www.motorola.com/mcu




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Re: What reset chip do you use? - Adrian Vos - May 2 0:45:00 2003

Excuse my ignorance here, but is it necessary to use a reset device if using
the S12DP256 in single chip mode (no external devices that need to be
sychronised for reset). I have done a couple of applications without using a
reset device, as the manual states that there is a delay of clock cycles
after the reset is released by a rising power supply, and I assumed that
this should be enough to ensure the power supply was stable before anything
starts running.

Am I at risk of internal Flash corruption if I just use a pull-up on the
reset line to the 5V supply as used by the S12 device? I am using a 4MHz
crystal, and a standard 7805 regulator (driving about 100uF capacitance, and
not much load).

Thanks,

Adrian

----- Original Message -----
From: "Roth Markus" <>
To: <>
Sent: Friday, May 02, 2003 3:36 PM
Subject: RE: [68HC12] What reset chip do you use? After similar problems with the Flash as you described, we used the
MAX6328UR29 (SOT23-3 package). For some safety reasons we had to use a very
low switch voltage of this reset device. But they are available at higher
(normal) voltages of 4...5V in 100mV steps from Maxim (Datasheet:
http://pdfserv.maxim-ic.com/arpdf/MAX6326-MAX6348.pdf). We use the open
drain device to allow the uC to pull down the reset line.
There ain't no more Flash problems after using this device.

Markus

> -----Original Message-----
> From: Paul Johnson [mailto:]
> Sent: Thursday, May 01, 2003 2:35 PM
> To:
> Subject: [68HC12] What reset chip do you use? > I am interested in anyone's experience with chips to control
> the reset line
> of the HC12 family, or specifically the MC68HC912DT128A. We
> are beginning
> to suspect that our circuitry may be culpable in corrupting
> flash memory.
>
> Thanks,
>
> Paul Johnson >
> --------------------------------------------------------
> To unsubscribe from this group, send an email to: > To learn more about Motorola Microcontrollers, please visit
> http://www.motorola.com/mcu This e-mail and any files transmitted with it (« Message ») are confidential
and may contain privileged information.
This Message is intended solely for the addressee(s). If you have received
this Message in error, please inform us promptly by reply e-mail then delete
the Message and destroy any printed copy of it.
Any unauthorized use, review, retransmission, dissemination, distribution,
printing or copying of this Message or any part thereof is strictly
prohibited.
E-mails are susceptible to alteration. Neither Technip-Coflexip nor any of
its subsidiaries and affiliates shall be liable for the Message if altered,
changed or falsified --------------------------------------------------------
To unsubscribe from this group, send an email to: To learn more about Motorola Microcontrollers, please visit
http://www.motorola.com/mcu
--------------------------------------------------------
To unsubscribe from this group, send an email to: To learn more about Motorola Microcontrollers, please visit
http://www.motorola.com/mcu






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RE: What reset chip do you use? - Oliver Betz - May 2 4:58:00 2003

Roth Markus wrote:

> After similar problems with the Flash as you described, we used the
> MAX6328UR29 (SOT23-3 package). For some safety reasons we had to use a very

What's the advantage of this 1$-IC over a 0,2$ *809?

Oliver
--
Oliver Betz, Muenchen



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Re: What reset chip do you use? - Oliver Betz - May 2 4:58:00 2003

Adrian Vos wrote:

> Excuse my ignorance here, but is it necessary to use a reset device if using
> the S12DP256 in single chip mode (no external devices that need to be

I don't know the S12DP256, and the OP asked for a MC68HC912DT128A.

It depends on the connected clock circuit and the Vcc rise time. The
D60A (likely the same as in the DT128A) xtal oscillator starts not
very fast, and there is no provision to inhibit erroneous clock
pulses. So if reset is released when there is still a weak (noisy)
clock signal, there is a significant probability of "code runaway"
(look for "runaway" in the docs!), I guess due to very short clock
pulses. The D60A clock input seems to have very little or no
hysteresis, IIRC a 50mVpp input signal was sufficient to drive the
uC. I already observed Flash corruption on a D60A with a MC34064
reset circuit!

I assume that Motorola improved the S12 clock circuit, but don't
really know. The "Clock Quality Checker" is a start, but wouldn't
cure the susceptibility to a weak, noisy clock signal. There had to
be a significant amount of hysteresis to suppress this.

Oliver
--
Oliver Betz, Muenchen



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RE: What reset chip do you use? - Roth Markus - May 2 5:12:00 2003

To Oliver

The hardware designer of this project is no longer in our company. The
problem occured after he went, and I chose this device in my function as
project leader and (sometimes) software developer. I am not a hardware
designer and chose a device that was used in another device in our company
with success.

However, this project has to meet a certain safety level (approved by TÜV
Automotive Munich ;-)) and it is hard to find qualified hardware. But I am
sure there are cheaper and equal reset devices out there...

Markus

> -----Original Message-----
> From: Oliver Betz [mailto:]
> Sent: Friday, May 02, 2003 11:59 AM
> To:
> Subject: RE: [68HC12] What reset chip do you use? > Roth Markus wrote:
>
> > After similar problems with the Flash as you described, we used the
> > MAX6328UR29 (SOT23-3 package). For some safety reasons we
> had to use a very
>
> What's the advantage of this 1$-IC over a 0,2$ *809?
>
> Oliver
> --
> Oliver Betz, Muenchen > ------------------------ Yahoo! Groups Sponsor
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>
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