This one is alsog good: "Art of Electronics" by Hill
and Horowitz.

-Sumukh


--- Bruce Cannon <brucecannon@bruc...> wrote:
> This book is out of print but I'll mention it
anyway
> because I see it used
> around a lot.  Not a textbook, but an invaluable
> compendium of hardware
> design rules of thumb:
> 
> "Circuit Designer's Companion" by Tim Williams.
> 
> Basically reads like the lab notebook of a really
> smart hardware designer
> who's been around the block a bunch of times.  A
> great hardware design
> quick reference.  Mostly overviews of each topic,
> but covers a practical
> minimum of every major gotcha, including bypassing,
> power and ground
> routing, high frequency design, emc, high-current
> design, etc. on a
> practical, hands-dirty, need-to-know-maths-only
> level.
> 
> If you ever see a copy, buy it.
> 
> --Bruce
> 
> > > There are design rules for this kind of thing
> that good
> > > text books will teach you about.
> >
> > You know a good one? ;-)
> 
> 
> 


__________________________________

This book is out of print but I'll mention it anyway because I see it
used
around a lot.  Not a textbook, but an invaluable compendium of hardware
design rules of thumb:

"Circuit Designer's Companion" by Tim Williams.

Basically reads like the lab notebook of a really smart hardware designer
who's been around the block a bunch of times.  A great hardware design
quick reference.  Mostly overviews of each topic, but covers a practical
minimum of every major gotcha, including bypassing, power and ground
routing, high frequency design, emc, high-current design, etc. on a
practical, hands-dirty, need-to-know-maths-only level.

If you ever see a copy, buy it.

--Bruce

> > There are design rules for this kind of thing
that good
> > text books will teach you about.
>
> You know a good one? ;-)

nobodyo@nobo... wrote:

> Hi,
> 
> 
>>>and how much time does
>>>it take to detect the transition (at 1.5 V) with a comparator and a
>>>comparator-ISR?
>>
>>The device isn't rated to operate at 1.5V.
> 
> 
> The device can operate with an input edge voltage of 1.5 V. This is within
the specification.
> Which input is faster for detecting a relative slow H->L transition
(edge) at that voltage: Digital input or Comparator input?
> 
> Regards
> 
> Rolf F.

oN THE SURFACE IT SHOULDN'T MAKE ANY DIFFERENCE, however I'd go for
the 
digital, since it will probably toggle at a lower threshold anyway.

I know English isn't your first langfuage, but you need to be a bit 
clearer, your last post read as if you were looking at responses based 
on supply voltage NOT input voltage.

Al

Hi,

>> and how much time does
>> it take to detect the transition (at 1.5 V) with a comparator and a
>> comparator-ISR?
>
> The device isn't rated to operate at 1.5V.

The device can operate with an input edge voltage of 1.5 V. This is within the
specification.
Which input is faster for detecting a relative slow H->L transition (edge) at
that voltage: Digital input or Comparator input?

Regards

Rolf F.

nobodyo@nobo... wrote:

> Hi,
> 
> 
>> Wait a minute.  You're having all these problems at 16Mhz?
> 
> 
> no, because at 16 MHz the MSP430 stopps at the beginning of main and
> TI recommends max. 8 MHz. I only wanted to know if 16 MHz system
> clock are possible when nearly all components (uart0, uart1, ADC12
> etc.) are active without self-flashing. Therefore i'm using a 8 MHz
> quartz with 15 pF capacitators and a 5.1 MOhm resistor.

What is the 5M resistor for? and what is the load rating of the crystal?


> Because the devices with the MSP430 have to work
for many years they
> are designed due to the recommendations of TI. An engineer at TI said
> that the circuit diagram and the real device is ok. The problem with
> the hangup during AM->LPM3 at 2.7 V is also present with a DCO system
> clock (approx. 4.8 MHz).
> 
> Regards
> 
> Rolf F.
> 
> 
> 
> ------------------------ Yahoo! Groups Sponsor
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> .
> 
> 
> 
> ">http://docs.yahoo.com/info/terms/
> 
> 
> 

nobodyo@nobo... wrote:

> Hi,
> 
> 
>> What is the fascination with the Gold Cap??
> 
> 
> Filtering the 3.3 supply. I wanted to use it to buffer the 3.3 V for 
> a MMC/SDC and EEPROM to store data during that time periode where the
>  primary supply voltage (5 V) is down and the gold cap buffered 3.3 V
>  is not down. This time periode is less then 100 ms when i short the
> 5 V supply. I thought this should be enough time but because the
> MSP430 fails at 2.7 V it is not.

>> What battery?.
> 
> 
> Li 3 V (usually around 3.05 V).

You're taking your main supply voltage down and trying to run from a
storage cap, but still have a back-up battery? Why? I'm sorry, but the 
logic of this totally eludes me. Post a schematic of the PSU at least.

>> The 2.7 critical level is only associated with
Flash programming, 
>> and high clock rates (> 5MHz). The MSP does not brown out at 2.6V, 
>> it will operate very reliably down to 1.8V with all peripherals 
>> running.

What I meant by the above statement is that provided your clock is less
than 5MHz the MSP430 is guaranteed to operate down to 1.8V, except for
flashing. Now the little graphs do seem to differ very slightly on the
maximum at 1.8V. The latest shows this as just 4.15MHz, I have an older
one around which I believe shows 5MHz. However, no matter what frequency
you run the core at the flash will not program reliably below 2.7V

> 
> 
> Not with the MSP430F149 REV L and the UARTS. I've tesed this with a 
> 16 MHz quartz (AT, HC 49/4H, 50 ppm, 7 pF) which i'm using for 
> overclocking PCs successfully and with that quarzt the MSP430 only 
> produces bullshit; communication over RS232 and SPI does not work. 
> With a oscilloscope i can see that the 16 MHz are stable but the MSP 
> does not work properly.  I've tried variations like no caps at the 
> quartz but no change even without communication to MMC/SDC or EEPROM 
> and, of course, without self-flashing.

Okay, after this very long thread you have only just mentioned that you 
are overclocking the beast. Have you thought to throttle it back to 
within the Ti ratings. Yes, I know, i talk about overclocking ALL the 
time, and do it regularly. That doesn't guarantee it'll work for you. 
There are so many pitfalls with overclocking a chip, that unless you 
really understand them it is doomed to failure. You can't simply jusy 
replace the 4MHz crystal with a 16MHz one.

For a start I overclock for a single reason, I need to crunch a lot of 
data, ie I need the CPU to run faster. There are many peripherals on the 
MSP430 that already require a divided clock, there is absolutely no 
sense, and nothing to be gained from overclocking these. These include 
the Flash, and ADC12. In general the things I overclock are timer 
captures, to give me better timing resolution, and the CPU, because my 
code typically is executing DSP like functions, ie many filters in real 
time.

>> I have run MSP430's with SCI/SPI at
voltages down to and even 
>> slightly below 1.8V, with no problems. I've run down to 2.4V at 
>> 16MHz in a freezer, and in an oven at the same temperatures,

Yes but, if the communications had failed I wouldn't start looking for a 
core fault, I'd back the clocks off, assuming that the thing I"d done 
out of spec was the cause of the problem.

> I've tested a 10, 11.0592 and 16 MHz quartz
at 3 V, 20C but at 16 
> MHz the MSP430 can't boot completely; maybe he hangs at 
> initialisation of uart0, uart1 or ADC12. With 11.0592 MHz he works 
> but not stable. With 10 MHz he seems to be stable (for some hours).

There are a lot of maybe's here, hasn't it occurred to you in all this

time to revert to clocking that is within the voltage spec Ti give, then 
wotrk it from there. You can see where the initialisation hangs up using 
C-Spy. Swapping out caps is meaningless, if you haven't got the correct 
caps in anyway you'll have difficulty.

> 
> 
> One question about changing fast to LPM3: How much time does it take 
> to detect a high->low-transition with a digital input

SLAS272C page 42. maximum inoput frequency to all ports at 2.2V = 8MHz, 
and at 3.0V = 10MHz.

  and an
> interrupt caused by that high->low-transition 

Interrupt latency is described as 6 cycles. However the document also 
states that the current instruction is first allowed to complete, hence 
since the longest executable instruction is 6 cycles I have alwasy 
assumed that interrupt latency is 6-12 cycles, plus the ISR uses 5 for 
RETI. hence the smallest possible ISR, containing nothing but RETI 
executes in 11 to 17 cycles. A typical meaningful ISR executes that 
clears the interrupt flag, and sets another flag, or sleep mode requires 
another 10 cycles typically. hence I assume that the fastest useful ISR 
is 21 - 27 cycles. Which I generally quote as 27 cycles.

> and how much time does 
> it take to detect the transition (at 1.5 V) with a comparator and a 
> comparator-ISR?

The device isn't rated to operate at 1.5V.

Al

Hi,

> Wait a minute.  You're having all these
problems at 16Mhz?

no, because at 16 MHz the MSP430 stopps at the beginning of main and TI
recommends max. 8 MHz. 
I only wanted to know if 16 MHz system clock are possible when nearly all
components (uart0, uart1, ADC12 etc.) are active without self-flashing. 
Therefore i'm using a 8 MHz quartz with 15 pF capacitators and a 5.1 MOhm
resistor.
Because the devices with the MSP430 have to work for many years they are
designed due to the recommendations of TI. An engineer at TI said that the
circuit diagram and the real device is ok.
The problem with the hangup during AM->LPM3 at 2.7 V is also present with a
DCO system clock (approx. 4.8 MHz).

Regards

Rolf F.

	Wait a minute.  You're having all these problems at 16Mhz?  Show me
*exactly* 
where in the datasheet it says that the part is rated for 16Mhz operation.  
All I see is 8Mhz.  

	Just because you can "overclock" a processor doesn't mean you
should.  And 
there are damn good reasons why it will fail.  Like the FLASH programming 
clock being derived from the system clock.  The limits for that are 257Khz 
lower and 476Khz upper.

	Basically, if you're trying to get it working at these speeds, and the
part 
isn't certified for it, you're wasting everyones time.

	--John

On Friday 26 September 2003 15:17 pm, nobodyo@nobo...
wrote:
>  Hi,
>
>  > What is the fascination with the Gold Cap??
>
>  Filtering the 3.3 supply. I wanted to use it to buffer the 3.3 V for a
> MMC/SDC and EEPROM to store data during that time periode where the primary
> supply voltage (5 V) is down and the gold cap buffered 3.3 V is not down.
> This time periode is less then 100 ms when i short the 5 V supply. I
> thought this should be enough time but because the MSP430 fails at 2.7 V it
> is not.
>
>  > What battery?.
>
>  Li 3 V (usually around 3.05 V).
>
>  > The 2.7 critical level is only associated with Flash programming, and
>  > high clock rates (> 5MHz). The MSP does not brown out at 2.6V, it
will
>  > operate very reliably down to 1.8V with all peripherals running.
>
>  Not with the MSP430F149 REV L and the UARTS. I've tesed this with a
16 MHz
> quartz (AT, HC 49/4H, 50 ppm, 7 pF) which i'm using for overclocking
PCs
> successfully and with that quarzt the MSP430 only produces bullshit;
> communication over RS232 and SPI does not work. With a oscilloscope i can
> see that the 16 MHz are stable but the MSP does not work properly.
I've
> tried variations like no caps at the quartz but no change even without
> communication to MMC/SDC or EEPROM and, of course, without self-flashing.
>
>  > I have run MSP430's with SCI/SPI at voltages down to and even
>  > slightly below 1.8V, with no problems. I've run down to 2.4V at
>  > 16MHz in a freezer, and in an oven at the same temperatures,
>
>  I've tested a 10, 11.0592 and 16 MHz quartz at 3 V, 20C but at 16
MHz the
> MSP430 can't boot completely; maybe he hangs at initialisation of
uart0,
> uart1 or ADC12. With 11.0592 MHz he works but not stable. With 10 MHz he
> seems to be stable (for some hours).
>
>
>  One question about changing fast to LPM3: How much time does it take to
> detect a high->low-transition with a digital input and an interrupt
caused
> by that high->low-transition and how much time does it take to detect
the
> transition (at 1.5 V) with a comparator and a comparator-ISR?
>
>  Regards
>
>  Rolf F.
>
>
>
>
> 
>
>
>
>
>
>
>  .
>
>
>
>  

Hi,

> What is the fascination with the Gold Cap??

Filtering the 3.3 supply. I wanted to use it to buffer the 3.3 V for a MMC/SDC
and EEPROM to store data 
during that time periode where the primary supply voltage (5 V) is down and the
gold cap buffered 3.3 V
is not down. This time periode is less then 100 ms when i short the 5 V supply.
I thought this should be 
enough time but because the MSP430 fails at 2.7 V it is not.


> What battery?.

Li 3 V (usually around 3.05 V).


> The 2.7 critical level is only associated with
Flash programming, and
> high clock rates (> 5MHz). The MSP does not brown out at 2.6V, it will
> operate very reliably down to 1.8V with all peripherals running.

Not with the MSP430F149 REV L and the UARTS. I've tesed this with a 16 MHz
quartz (AT, HC 49/4H, 50 
ppm, 7 pF) which i'm using for overclocking PCs successfully and with that
quarzt the MSP430 only produces
bullshit; communication over RS232 and SPI does not work. With a oscilloscope i
can see that the 16 MHz 
are stable but the MSP does not work properly.  I've tried variations like
no caps at the quartz but no change even without communication to MMC/SDC or
EEPROM and, of course, without self-flashing.


> I have run MSP430's with SCI/SPI at voltages
down to and even
> slightly below 1.8V, with no problems. I've run down to 2.4V at
> 16MHz in a freezer, and in an oven at the same temperatures,

I've tested a 10, 11.0592 and 16 MHz quartz at 3 V, 20C but at 16 MHz the
MSP430 can't boot completely; maybe he hangs at initialisation of uart0,
uart1 or ADC12. With 11.0592 MHz he works but not stable. With 10 MHz he seems
to be stable (for some hours).


One question about changing fast to LPM3: How much time does it take to detect a
high->low-transition with a digital input and an interrupt caused by that
high->low-transition and how much time does it take to detect the transition
(at 1.5 V) with a comparator and a comparator-ISR?

Regards

Rolf F.

J.C. Wren wrote:
> 	I'm not clear if you're using the Gold
Cap as a power supply or as an attempt 
> to filter the 3.3V regulator, but large caps like that are useless at 
> filtering high frequency ripple.  A general rule of thumb design is to use 
> 1000uf or so at the output of the main stage regulator.  Sometimes more, 
> sometimes less, but that will supress almost all 60hz ripple under normal 
> loads.  Use a 4.7uf tantalum (preferred, expensive) or a 4.7uf electrolytic

> for every 3-4 chips, and .1uf on EVERY chip.  If you have a lot of high 
> frequency around your device, you may also want a .047uf with every couple 
> chips.
> 
> 	There are design rules for this kind of thing that good text books will
teach 
> you about.  
You know a good one? ;-)


> But if you're going to ad-hoc a PSU, these
values are pretty 
> good.  If your circuit draws a lot of current, or your using TTL chips (not

> CMOS, HC, LVC, but real TTL), then you want 10uf near every couple chips.
> 
> 	If you're running a 2 layer board (which there is nothing
intrinsically wrong 
> with), you want your ground and power to form a loop, not meander around
the 
> board with "legs" sticking out here and there (at least, not long
ones).  
>
___snip____


Greetz,

	Georg