We would like to program the FLASH with Vcc at 2.5 volts. It's
spec'd 
at 2.7 volts although a TI presenter at a February seminar mentioned 
that lowering the spec was being considered. The 249 which is due 
early next year was projected to be programmable down to 2.2 volts.

I have done some preliminary tests down to 2.0 volts that appear to 
work. I plan on more extensive testing. Has any one done any testing 
at programming FLASH at lower voltages? What exact FLASH programming 
failures should be expected at unexceptablely low voltage? 

It appears to be quite temperature dependant from my testing. I have 
done a lot of flash read write testing, basically trying to life test 
flash for use as a long term logger. As a result of this testing I have 
decided NOT to trust flash programming below 3V0.

Al

mjruley wrote:

> We would like to program the FLASH with Vcc at 2.5
volts. It's spec'd 
> at 2.7 volts although a TI presenter at a February seminar mentioned 
> that lowering the spec was being considered. The 249 which is due 
> early next year was projected to be programmable down to 2.2 volts.
> 
> I have done some preliminary tests down to 2.0 volts that appear to 
> work. I plan on more extensive testing. Has any one done any testing 
> at programming FLASH at lower voltages? What exact FLASH programming 
> failures should be expected at unexceptablely low voltage? 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 

"As a result of this testing I have decided NOT to trust flash 
programming below 3V0."
What clock speed is that at?  Or does it matter?

- Miles

onestone wrote:

> It appears to be quite temperature dependant from
my testing. I have
> done a lot of flash read write testing, basically trying to life test
> flash for use as a long term logger. As a result of this testing I have
> decided NOT to trust flash programming below 3V0.
>
> Al
>
> mjruley wrote:
>
> > We would like to program the FLASH with Vcc at 2.5 volts. It's
spec'd
> > at 2.7 volts although a TI presenter at a February seminar mentioned
> > that lowering the spec was being considered. The 249 which is due
> > early next year was projected to be programmable down to 2.2 volts.
> >
> > I have done some preliminary tests down to 2.0 volts that appear to
> > work. I plan on more extensive testing. Has any one done any testing
> > at programming FLASH at lower voltages? What exact FLASH programming
> > failures should be expected at unexceptablely low voltage?
> >
> >
> >
>

On Thu, 15 Jul 2004 01:06:44 -0400, Miles wrote:

>"As a result of this testing I have decided
NOT to trust flash 
>programming below 3V0."

>What clock speed is that at?  Or does it matter?

The clock speed for erasure and programming is specified in the data sheets and
it's in the range between 257kHz and 476kHz.

Jon

Clock speed is irelevant, only the FTG timing, which I've tried at
lower 
and higher ends of the range.

aL

Miles Gazic wrote:
> "As a result of this testing I have decided NOT to trust flash 
> programming below 3V0."
> What clock speed is that at?  Or does it matter?
> 
> - Miles
> 
> onestone wrote:
> 
> 
>>It appears to be quite temperature dependant from my testing. I have
>>done a lot of flash read write testing, basically trying to life test
>>flash for use as a long term logger. As a result of this testing I have
>>decided NOT to trust flash programming below 3V0.
>>
>>Al
>>
>>mjruley wrote:
>>
>>
>>>We would like to program the FLASH with Vcc at 2.5 volts. It's
spec'd
>>>at 2.7 volts although a TI presenter at a February seminar mentioned
>>>that lowering the spec was being considered. The 249 which is due
>>>early next year was projected to be programmable down to 2.2 volts.
>>>
>>>I have done some preliminary tests down to 2.0 volts that appear to
>>>work. I plan on more extensive testing. Has any one done any testing
>>>at programming FLASH at lower voltages? What exact FLASH programming
>>>failures should be expected at unexceptablely low voltage?
>>>
>>>
>>>
>>
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 

On Thu, 15 Jul 2004 15:55:11 +0930, Al wrote:

>Clock speed is irelevant, only the FTG timing

Yes, my mistake in terms when I replied!

Jon

" Clock speed is irelevant, only the FTG timing, which I've tried
at lower
and higher ends of the range."

That's what I've read in the TI User Guide.  In several product 
datasheets however, there is a chart showing allowable clock frequency 
as a function of supply voltage, for program execution and for flash 
memory programming.  The chart indicates that the max clock speed when 
flashing at 2.7V is about 6MHz, and it increases linearly to 8MHz at 3.6V.

see page 24 of this doc, for an example: 
http://focus.ti.com/lit/ds/slas272f/slas272f.pdf

I've been trying to write to flash with an 8MHz clock at 3.3V, and have 
had occasional corruption.  After seeing that document, I'm going to try 
setting the clock speed to 4MHz before writing to flash, and seeing if I 
have better luck.

- Miles

onestone wrote:

> Clock speed is irelevant, only the FTG timing,
which I've tried at lower
> and higher ends of the range.
>
> aL
>
> Miles Gazic wrote:
> > "As a result of this testing I have decided NOT to trust flash
> > programming below 3V0."
> > What clock speed is that at?  Or does it matter?
> >
> > - Miles
> >
> > onestone wrote:
> >
> >
> >>It appears to be quite temperature dependant from my testing. I
have
> >>done a lot of flash read write testing, basically trying to life
test
> >>flash for use as a long term logger. As a result of this testing I
have
> >>decided NOT to trust flash programming below 3V0.
> >>
> >>Al
> >>
> >>mjruley wrote:
> >>
> >>
> >>>We would like to program the FLASH with Vcc at 2.5 volts.
It's spec'd
> >>>at 2.7 volts although a TI presenter at a February seminar
mentioned
> >>>that lowering the spec was being considered. The 249 which is
due
> >>>early next year was projected to be programmable down to 2.2
volts.
> >>>
> >>>I have done some preliminary tests down to 2.0 volts that
appear to
> >>>work. I plan on more extensive testing. Has any one done any
testing
> >>>at programming FLASH at lower voltages? What exact FLASH
programming
> >>>failures should be expected at unexceptablely low voltage?
> >>>
> >>>
> >>>
> >>
> >
> >
> >
> > .
> >
> > 
> > Yahoo! Groups Links

I've pushed my clocks out to 16MHz. My default operating voltage is 
3.3V. As long as the FTG is within spec the main clock signal doesn't 
seem to matter. The 16MHz is also reliable within the same temp/voltage 
bands that the flash is. In fact most parts will start and stabilise a 
properly loaded 16MHz crystal down to 2.2V, and then run quite happily 
on it. There has been much historical trafic regarding this.

Al

Miles Gazic wrote:

> " Clock speed is irelevant, only the FTG
timing, which I've tried at lower
> and higher ends of the range."
> 
> That's what I've read in the TI User Guide.  In several product 
> datasheets however, there is a chart showing allowable clock frequency 
> as a function of supply voltage, for program execution and for flash 
> memory programming.  The chart indicates that the max clock speed when 
> flashing at 2.7V is about 6MHz, and it increases linearly to 8MHz at 3.6V.
> 
> see page 24 of this doc, for an example: 
> http://focus.ti.com/lit/ds/slas272f/slas272f.pdf
> 
> I've been trying to write to flash with an 8MHz clock at 3.3V, and
have 
> had occasional corruption.  After seeing that document, I'm going to
try 
> setting the clock speed to 4MHz before writing to flash, and seeing if I 
> have better luck.
> 
> - Miles
> 
> onestone wrote:
> 
> 
>>Clock speed is irelevant, only the FTG timing, which I've tried at
lower
>>and higher ends of the range.
>>
>>aL
>>
>>Miles Gazic wrote:
>>
>>>"As a result of this testing I have decided NOT to trust flash
>>>programming below 3V0."
>>>What clock speed is that at?  Or does it matter?
>>>
>>>- Miles
>>>
>>>onestone wrote:
>>>
>>>
>>>
>>>>It appears to be quite temperature dependant from my testing. I
have
>>>>done a lot of flash read write testing, basically trying to life
test
>>>>flash for use as a long term logger. As a result of this testing
I have
>>>>decided NOT to trust flash programming below 3V0.
>>>>
>>>>Al
>>>>
>>>>mjruley wrote:
>>>>
>>>>
>>>>
>>>>>We would like to program the FLASH with Vcc at 2.5 volts.
It's spec'd
>>>>>at 2.7 volts although a TI presenter at a February seminar
mentioned
>>>>>that lowering the spec was being considered. The 249 which
is due
>>>>>early next year was projected to be programmable down to 2.2
volts.
>>>>>
>>>>>I have done some preliminary tests down to 2.0 volts that
appear to
>>>>>work. I plan on more extensive testing. Has any one done any
testing
>>>>>at programming FLASH at lower voltages? What exact FLASH
programming
>>>>>failures should be expected at unexceptablely low voltage?
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>>.
>>>
>>>
>>>Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 

That's good to know.  It sounds like my flashing problems are not due
to 
the supply voltage DC value, then.

How much voise is on your 3.3V supply, if you don't mind my asking?  The 
hardware guys working on my project didn't filter the 3.3 very much, 
since (in their words) it's for digital devices, and hence not very 
important.  I see a 50mv peak-to-peak sawtooth with a 15khz frequency, 
as well as 20mv peak-to-peak at a much higher frequency.  Putting a big 
electrolytic cap on the 3.3v line knocks the sawtooth flat, but the 
higher frequency component remains.

Should I get the hardware guys to filter the 3.3V better, or do you 
think my problem lies elsewhere?

Thanks,
Miles

onestone wrote:

> I've pushed my clocks out to 16MHz. My
default operating voltage is
> 3.3V. As long as the FTG is within spec the main clock signal doesn't
> seem to matter. The 16MHz is also reliable within the same temp/voltage
> bands that the flash is. In fact most parts will start and stabilise a
> properly loaded 16MHz crystal down to 2.2V, and then run quite happily
> on it. There has been much historical trafic regarding this.
>
> Al
>
> Miles Gazic wrote:
>
> > " Clock speed is irelevant, only the FTG timing, which I've
tried at 
> lower
> > and higher ends of the range."
> >
> > That's what I've read in the TI User Guide.  In several
product
> > datasheets however, there is a chart showing allowable clock frequency
> > as a function of supply voltage, for program execution and for flash
> > memory programming.  The chart indicates that the max clock speed when
> > flashing at 2.7V is about 6MHz, and it increases linearly to 8MHz at 
> 3.6V.
> >
> > see page 24 of this doc, for an example:
> > http://focus.ti.com/lit/ds/slas272f/slas272f.pdf
> >
> > I've been trying to write to flash with an 8MHz clock at 3.3V,
and have
> > had occasional corruption.  After seeing that document, I'm going
to 
> try
> > setting the clock speed to 4MHz before writing to flash, and seeing 
> if I
> > have better luck.
> >
> > - Miles
> >
> > onestone wrote:
> >
> >
> >>Clock speed is irelevant, only the FTG timing, which I've
tried at lower
> >>and higher ends of the range.
> >>
> >>aL
> >>
> >>Miles Gazic wrote:
> >>
> >>>"As a result of this testing I have decided NOT to trust
flash
> >>>programming below 3V0."
> >>>What clock speed is that at?  Or does it matter?
> >>>
> >>>- Miles
> >>>
> >>>onestone wrote:
> >>>
> >>>
> >>>
> >>>>It appears to be quite temperature dependant from my
testing. I have
> >>>>done a lot of flash read write testing, basically trying to
life test
> >>>>flash for use as a long term logger. As a result of this
testing I 
> have
> >>>>decided NOT to trust flash programming below 3V0.
> >>>>
> >>>>Al
> >>>>
> >>>>mjruley wrote:
> >>>>
> >>>>
> >>>>
> >>>>>We would like to program the FLASH with Vcc at 2.5
volts. It's spec'd
> >>>>>at 2.7 volts although a TI presenter at a February
seminar mentioned
> >>>>>that lowering the spec was being considered. The 249
which is due
> >>>>>early next year was projected to be programmable down
to 2.2 volts.
> >>>>>
> >>>>>I have done some preliminary tests down to 2.0 volts
that appear to
> >>>>>work. I plan on more extensive testing. Has any one
done any testing
> >>>>>at programming FLASH at lower voltages? What exact
FLASH programming
> >>>>>failures should be expected at unexceptablely low
voltage?
> >>>>>

I use batteries. Li-poly, regulated, then cleaned up to < 10mV p-p of 
noise visible on a 100MHz scope. I would look into your flash routines, 
is there any possibility that ints are still enabled, or the WDT might 
be active. Are you using block writes? I avoid these, they do have some 
reliability issues, and require more than 1 pass, effectively rendering 
it a useless mode.

Al

Miles Gazic wrote:

> That's good to know.  It sounds like my
flashing problems are not due to 
> the supply voltage DC value, then.
> 
> How much voise is on your 3.3V supply, if you don't mind my asking? 
The 
> hardware guys working on my project didn't filter the 3.3 very much, 
> since (in their words) it's for digital devices, and hence not very 
> important.  I see a 50mv peak-to-peak sawtooth with a 15khz frequency, 
> as well as 20mv peak-to-peak at a much higher frequency.  Putting a big 
> electrolytic cap on the 3.3v line knocks the sawtooth flat, but the 
> higher frequency component remains.
> 
> Should I get the hardware guys to filter the 3.3V better, or do you 
> think my problem lies elsewhere?
> 
> Thanks,
> Miles
> 
> onestone wrote:
> 
> 
>>I've pushed my clocks out to 16MHz. My default operating voltage is
>>3.3V. As long as the FTG is within spec the main clock signal
doesn't
>>seem to matter. The 16MHz is also reliable within the same temp/voltage
>>bands that the flash is. In fact most parts will start and stabilise a
>>properly loaded 16MHz crystal down to 2.2V, and then run quite happily
>>on it. There has been much historical trafic regarding this.
>>
>>Al
>>
>>Miles Gazic wrote:
>>
>>
>>>" Clock speed is irelevant, only the FTG timing, which
I've tried at 
>>
>>lower
>>
>>>and higher ends of the range."
>>>
>>>That's what I've read in the TI User Guide.  In several
product
>>>datasheets however, there is a chart showing allowable clock
frequency
>>>as a function of supply voltage, for program execution and for flash
>>>memory programming.  The chart indicates that the max clock speed
when
>>>flashing at 2.7V is about 6MHz, and it increases linearly to 8MHz at

>>
>>3.6V.
>>
>>>see page 24 of this doc, for an example:
>>>http://focus.ti.com/lit/ds/slas272f/slas272f.pdf
>>>
>>>I've been trying to write to flash with an 8MHz clock at 3.3V,
and have
>>>had occasional corruption.  After seeing that document, I'm
going to 
>>
>>try
>>
>>>setting the clock speed to 4MHz before writing to flash, and seeing 
>>
>>if I
>>
>>>have better luck.
>>>
>>>- Miles
>>>
>>>onestone wrote:
>>>
>>>
>>>
>>>>Clock speed is irelevant, only the FTG timing, which I've
tried at lower
>>>>and higher ends of the range.
>>>>
>>>>aL
>>>>
>>>>Miles Gazic wrote:
>>>>
>>>>
>>>>>"As a result of this testing I have decided NOT to
trust flash
>>>>>programming below 3V0."
>>>>>What clock speed is that at?  Or does it matter?
>>>>>
>>>>>- Miles
>>>>>
>>>>>onestone wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>It appears to be quite temperature dependant from my
testing. I have
>>>>>>done a lot of flash read write testing, basically trying
to life test
>>>>>>flash for use as a long term logger. As a result of this
testing I 
>>
>>have
>>
>>>>>>decided NOT to trust flash programming below 3V0.
>>>>>>
>>>>>>Al
>>>>>>
>>>>>>mjruley wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>We would like to program the FLASH with Vcc at 2.5
volts. It's spec'd
>>>>>>>at 2.7 volts although a TI presenter at a February
seminar mentioned
>>>>>>>that lowering the spec was being considered. The 249
which is due
>>>>>>>early next year was projected to be programmable
down to 2.2 volts.
>>>>>>>
>>>>>>>I have done some preliminary tests down to 2.0 volts
that appear to
>>>>>>>work. I plan on more extensive testing. Has any one
done any testing
>>>>>>>at programming FLASH at lower voltages? What exact
FLASH programming
>>>>>>>failures should be expected at unexceptablely low
voltage?
>>>>>>>
> 
> 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
>