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Re: [Electronics_101] Re: SPI interfacing - How long can external connections be?

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  • Roy J. Tellason
    ... A bunch of wire on a spool is also going to have some inductance, there, much more so than just a wire run to somewhere... -- Member of the toughest,
    Message 1 of 16 , Apr 30, 2006
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      On Sunday 30 April 2006 04:55 pm, lcdpublishing wrote:
      > Well, I know for sure what won't work!
      >
      > I had a 100' spool of 24 gauge solid core wire handy with both ends of
      > the cable exposed. I stripped off some conductors, spliced it into the
      > bread board circuit for the SPI wires. No-go, so, now I know!
      >
      > 100 feet - too long for SPI ;-)

      A bunch of wire on a spool is also going to have some inductance, there,
      much more so than just a wire run to somewhere...

      --
      Member of the toughest, meanest, deadliest, most unrelenting -- and
      ablest -- form of life in this section of space, a critter that can
      be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
      -
      Information is more dangerous than cannon to a society ruled by lies. --James
      M Dakin
    • lcdpublishing
      HI ROy, In reality, I would have been very surprised had it worked! When I was first working out some serial communications software about 20 years ago, I
      Message 2 of 16 , May 1, 2006
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        HI ROy,

        In reality, I would have been very surprised had it worked! When I
        was first working out some serial communications software about 20
        years ago, I used all short cables and PC-PC for testing. Then to
        find the distance limitation with RS232, I had four, 1000 foot
        spools of cable on hand. I started out with one spool, then two,
        then on the third one it failed. At the time I had no idea why, but
        I was aware that having the cable on the spool was a "worst case"
        situation.

        Today's test I am going to cut off about a 25 foot section of the
        cable I tried for SPI, and see if that works. If not, I will keep
        cutting it down till it does.




        --- In Electronics_101@yahoogroups.com, "Roy J. Tellason"
        <rtellason@...> wrote:
        >
        > On Sunday 30 April 2006 04:55 pm, lcdpublishing wrote:
        > > Well, I know for sure what won't work!
        > >
        > > I had a 100' spool of 24 gauge solid core wire handy with both
        ends of
        > > the cable exposed. I stripped off some conductors, spliced it
        into the
        > > bread board circuit for the SPI wires. No-go, so, now I know!
        > >
        > > 100 feet - too long for SPI ;-)
        >
        > A bunch of wire on a spool is also going to have some inductance,
        there,
        > much more so than just a wire run to somewhere...
        >
        > --
        > Member of the toughest, meanest, deadliest, most unrelenting -- and
        > ablest -- form of life in this section of space, a critter that
        can
        > be killed but can't be tamed. --Robert A. Heinlein, "The Puppet
        Masters"
        > -
        > Information is more dangerous than cannon to a society ruled by
        lies. --James
        > M Dakin
        >
      • lcdpublishing
        It does appear that 20 feet of cable will work for SPI. The length is approximate, but I think it is close to 20 . The speed at which I am communicating at
        Message 3 of 16 , May 1, 2006
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          It does appear that 20 feet of cable will work for SPI. The length
          is approximate, but I think it is close to 20'.

          The speed at which I am communicating at though is a bit confusing
          based on the documentation I am working with in the BASCOM manual.
          If I am interpreting it correctly, I am communicating at 1/16 clock
          speed. So 18.432 Mhz xtal 18,432,000 / 16 = 1,152,000 bits per
          second.

          If I understand everything correctly, this is very good news for
          this project! Things just got a lot faster and better.

          CHris



          --- In Electronics_101@yahoogroups.com, "lcdpublishing"
          <lcdpublishing@...> wrote:
          >
          > HI ROy,
          >
          > In reality, I would have been very surprised had it worked! When
          I
          > was first working out some serial communications software about 20
          > years ago, I used all short cables and PC-PC for testing. Then to
          > find the distance limitation with RS232, I had four, 1000 foot
          > spools of cable on hand. I started out with one spool, then two,
          > then on the third one it failed. At the time I had no idea why,
          but
          > I was aware that having the cable on the spool was a "worst case"
          > situation.
          >
          > Today's test I am going to cut off about a 25 foot section of the
          > cable I tried for SPI, and see if that works. If not, I will keep
          > cutting it down till it does.
          >
          >
          >
          >
          > --- In Electronics_101@yahoogroups.com, "Roy J. Tellason"
          > <rtellason@> wrote:
          > >
          > > On Sunday 30 April 2006 04:55 pm, lcdpublishing wrote:
          > > > Well, I know for sure what won't work!
          > > >
          > > > I had a 100' spool of 24 gauge solid core wire handy with both
          > ends of
          > > > the cable exposed. I stripped off some conductors, spliced it
          > into the
          > > > bread board circuit for the SPI wires. No-go, so, now I know!
          > > >
          > > > 100 feet - too long for SPI ;-)
          > >
          > > A bunch of wire on a spool is also going to have some
          inductance,
          > there,
          > > much more so than just a wire run to somewhere...
          > >
          > > --
          > > Member of the toughest, meanest, deadliest, most unrelenting --
          and
          > > ablest -- form of life in this section of space, a critter that
          > can
          > > be killed but can't be tamed. --Robert A. Heinlein, "The Puppet
          > Masters"
          > > -
          > > Information is more dangerous than cannon to a society ruled by
          > lies. --James
          > > M Dakin
          > >
          >
        • Roy J. Tellason
          ... ... You might find it informative to put a scope on that signal, without the wire and then with it, both at the source end and at the other end as
          Message 4 of 16 , May 1, 2006
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            On Monday 01 May 2006 09:02 am, lcdpublishing wrote:
            > It does appear that 20 feet of cable will work for SPI. The length
            > is approximate, but I think it is close to 20'.

            <...>

            > > In reality, I would have been very surprised had it worked! When
            > > I was first working out some serial communications software about 20
            > > years ago, I used all short cables and PC-PC for testing. Then to
            > > find the distance limitation with RS232, I had four, 1000 foot
            > > spools of cable on hand. I started out with one spool, then two,
            > > then on the third one it failed. At the time I had no idea why,
            > > but I was aware that having the cable on the spool was a "worst case"
            > > situation.
            > >
            > > Today's test I am going to cut off about a 25 foot section of the
            > > cable I tried for SPI, and see if that works. If not, I will keep
            > > cutting it down till it does.
            > >
            > > --- In Electronics_101@yahoogroups.com, "Roy J. Tellason"
            > >
            > > <rtellason@> wrote:
            > > > On Sunday 30 April 2006 04:55 pm, lcdpublishing wrote:
            > > > > Well, I know for sure what won't work!
            > > > >
            > > > > I had a 100' spool of 24 gauge solid core wire handy with both
            > > > > ends of the cable exposed. I stripped off some conductors, spliced it
            > > > > into the bread board circuit for the SPI wires. No-go, so, now I
            > > > > know!
            > > > >
            > > > > 100 feet - too long for SPI ;-)
            > > >
            > > > A bunch of wire on a spool is also going to have some
            > > > inductance, there,
            > >
            > > > much more so than just a wire run to somewhere...

            You might find it informative to put a scope on that signal, without the wire
            and then with it, both at the source end and at the other end as well...

            --
            Member of the toughest, meanest, deadliest, most unrelenting -- and
            ablest -- form of life in this section of space, a critter that can
            be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
            -
            Information is more dangerous than cannon to a society ruled by lies. --James
            M Dakin
          • lcdpublishing
            Roy, I will do when I get the cable in that I plan on using for this. By chance, can you give me a hint as to what sort of good and bad things I should be
            Message 5 of 16 , May 1, 2006
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              Roy, I will do when I get the cable in that I plan on using for
              this. By chance, can you give me a hint as to what sort of good and
              bad things I should be looking for?

              Right now, my technique on the scope is more or less, if I see two
              horizontal lines - spaced apart at the voltage and duration I think
              they should be - I am happy.

              Chris



              --- In Electronics_101@yahoogroups.com, "Roy J. Tellason"
              <rtellason@...> wrote:
              >
              > On Monday 01 May 2006 09:02 am, lcdpublishing wrote:
              > > It does appear that 20 feet of cable will work for SPI. The
              length
              > > is approximate, but I think it is close to 20'.
              >
              > <...>
              >
              > > > In reality, I would have been very surprised had it worked!
              When
              > > > I was first working out some serial communications software
              about 20
              > > > years ago, I used all short cables and PC-PC for testing.
              Then to
              > > > find the distance limitation with RS232, I had four, 1000 foot
              > > > spools of cable on hand. I started out with one spool, then
              two,
              > > > then on the third one it failed. At the time I had no idea
              why,
              > > > but I was aware that having the cable on the spool was
              a "worst case"
              > > > situation.
              > > >
              > > > Today's test I am going to cut off about a 25 foot section of
              the
              > > > cable I tried for SPI, and see if that works. If not, I will
              keep
              > > > cutting it down till it does.
              > > >
              > > > --- In Electronics_101@yahoogroups.com, "Roy J. Tellason"
              > > >
              > > > <rtellason@> wrote:
              > > > > On Sunday 30 April 2006 04:55 pm, lcdpublishing wrote:
              > > > > > Well, I know for sure what won't work!
              > > > > >
              > > > > > I had a 100' spool of 24 gauge solid core wire handy with
              both
              > > > > > ends of the cable exposed. I stripped off some conductors,
              spliced it
              > > > > > into the bread board circuit for the SPI wires. No-go,
              so, now I
              > > > > > know!
              > > > > >
              > > > > > 100 feet - too long for SPI ;-)
              > > > >
              > > > > A bunch of wire on a spool is also going to have some
              > > > > inductance, there,
              > > >
              > > > > much more so than just a wire run to somewhere...
              >
              > You might find it informative to put a scope on that signal,
              without the wire
              > and then with it, both at the source end and at the other end as
              well...
              >
              > --
              > Member of the toughest, meanest, deadliest, most unrelenting -- and
              > ablest -- form of life in this section of space, a critter that
              can
              > be killed but can't be tamed. --Robert A. Heinlein, "The Puppet
              Masters"
              > -
              > Information is more dangerous than cannon to a society ruled by
              lies. --James
              > M Dakin
              >
            • Roy J. Tellason
              ... Nope, I just know that the signal _will_ change and that it might be instructive to see how it changes... -- Member of the toughest, meanest, deadliest,
              Message 6 of 16 , May 1, 2006
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                On Monday 01 May 2006 10:48 am, lcdpublishing wrote:
                > Roy, I will do when I get the cable in that I plan on using for
                > this. By chance, can you give me a hint as to what sort of good and
                > bad things I should be looking for?

                Nope, I just know that the signal _will_ change and that it might be
                instructive to see how it changes...

                --
                Member of the toughest, meanest, deadliest, most unrelenting -- and
                ablest -- form of life in this section of space, a critter that can
                be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
                -
                Information is more dangerous than cannon to a society ruled by lies. --James
                M Dakin
              • Shawn Standfast
                ... Transmission lines all have four basic properties inherient to them. They are: 1) resistance 2) inductance 3) capacitance 4) conductance. The resistance
                Message 7 of 16 , May 1, 2006
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                  --- lcdpublishing <lcdpublishing@...> wrote:

                  > Roy, I will do when I get the cable in that I plan
                  > on using for
                  > this. By chance, can you give me a hint as to what
                  > sort of good and
                  > bad things I should be looking for?

                  Transmission lines all have four basic properties
                  inherient to them. They are: 1) resistance 2)
                  inductance 3) capacitance 4) conductance.

                  The resistance and inductance are in series with the
                  load at the other end and the capacitance and
                  conductance are in parallel with the load. What this
                  means is that your transmission line will behave as a
                  filter when a signal is passed along it. This has
                  several side affects associated with it. I will
                  discuss these in a moment. First let me digress into
                  an aside about signals.

                  According to Fourier, any real signal can be expressed
                  as a sumation of an infinate combination of sines and
                  cosines; each with a different frequency and
                  amplitude. The frequencies of each "component" are
                  integer multiples of the fundimental frequency. This
                  is what people are refering to when they talk about
                  n-th order harmonic frequencies (i.e. the third
                  harmonic for example). In digital circuits, our
                  transmission signal is a square wave. Transforming
                  this into its Fourier series yeilds a combination of
                  sine waves with odd-numbered multiples of the
                  fundimental frequency. You don't really need to grasp
                  this fully right now but it is revelant for your case.

                  Getting back to the transmission line properties, let
                  me remind you that a transmission line will behave as
                  a passive filter when the line lengths get long
                  enough. This results in two distinct effects on a
                  signal that is being transmitted on it. 1) Phase
                  shift 2) Voltage reflection.

                  PHASE SHIFT -- All passive filters will create some
                  sort of a phase shift of any AC signal that is passed
                  through it. Whether or not the shift is positive or
                  negative will depend upon the frequency of the signal
                  and the type of filter it passes through. Recall that
                  our digital square-wave is actually composed of an
                  infinate combination of sine waves. When this type of
                  wave is sent along a transmission line the wave can
                  become "distorted" when it comes out the other end.
                  This is because the "line filter" has shifted the
                  phase of some of the square wave's harmonics. So what
                  you should be looking for on the output end of your
                  line will be ringing on your transitions and rounding
                  of your signal edges. If your line is really long, or
                  poorly constructed, you might even see something that
                  looks more like an audio signal rather than a
                  square-wave.

                  VOLTAGE REFLECTION -- The second characteristic that
                  must be accounted for is voltage reflection. What
                  this describes is the fact that that not all power
                  transmitted on the line will be transfered to the
                  load. Some of it will be reflected back to the
                  source. The effect is similar to the one observed
                  when you take a string and tie one end to a wall and
                  then take the other end and shake it up and down to
                  create a wave on the string. When the wave reaches
                  the wall, the wave "bounces back" towards you. This
                  is onset by a mismatch in impedances between the
                  source, transmission line, and load. When the voltage
                  is reflected back to the source, if the source and
                  line impedences don't match the wave will then be
                  reflected back down to the load again. This results
                  in what is called a "standing wave" and in "ideal"
                  conditions can continue forever. One effect that can
                  be caused by this standing wave is if the standing
                  wave happens to be in phase with the signal at the
                  load then the voltages add together. This can cause
                  the voltage across the load to increase greatly. The
                  same is true at the source. When the standing wave is
                  in phase with the signal at the source, the voltage at
                  the source can increase greatly.

                  The opposite is also true. If the standing wave is
                  180 degrees out of phase with the signal and the
                  relative amplitudes of each are similar, then the
                  signal will in effect be canceled out at the load (or
                  source depending on which end of the line you're on.)
                  This is why impedence matching is so important between
                  the source, line, and load. If the impedences match
                  then a standing wave will not be seen. What you
                  should look for to determine if this is happening is
                  check your voltages. If you have a dramatic increase
                  or decrease on either side of the line then you
                  probably need to adjust the length of your line.
                  Also, check each of the components on either side of
                  the line. If they are getting hot then that probably
                  indicates a problem as well.

                  I forget the exact length, but I believe these effects
                  start to become noticeable when the length of your
                  line is 1/100th that of the signal wavelength but I'll
                  have to look this up to be sure. At your voltages and
                  frequencies, you will probably have to worry more
                  about phase shift than voltage reflection but it never
                  hurts to check for both. Also, the degree in which
                  these effects are manifested depend upon the type of
                  transmission line used.

                  If you want more information on either the Fourier
                  transform or transmission line properties do a google
                  search. There is quite a bit of information out there
                  on both topics.

                  Hope this helps you find what you are looking for.

                  Shawn

                  http://www.geocities.com/sstandfast

                  __________________________________________________
                  Do You Yahoo!?
                  Tired of spam? Yahoo! Mail has the best spam protection around
                  http://mail.yahoo.com
                • lcdpublishing
                  Facinating Shawn! While some (well, much) of it is over my head at this time, I get the gist of what you are saying and describing. I am hoping, (odd someone
                  Message 8 of 16 , May 1, 2006
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                    Facinating Shawn! While some (well, much) of it is over my head at
                    this time, I get the gist of what you are saying and describing.

                    I am hoping, (odd someone hopes for problems) that I will see some
                    of these effects when I get the cable and put a scope on this
                    signal. It sure would be great to actually "See" and "Measure" the
                    cause and effects of this sort of thing.

                    I will have to re-read this post a number of times to gain more from
                    it. So I may be back at you will questions further down the road.

                    Thanks!!!!

                    Chris






                    --- In Electronics_101@yahoogroups.com, Shawn Standfast
                    <sstandfast@...> wrote:
                    >
                    > --- lcdpublishing <lcdpublishing@...> wrote:
                    >
                    > > Roy, I will do when I get the cable in that I plan
                    > > on using for
                    > > this. By chance, can you give me a hint as to what
                    > > sort of good and
                    > > bad things I should be looking for?
                    >
                    > Transmission lines all have four basic properties
                    > inherient to them. They are: 1) resistance 2)
                    > inductance 3) capacitance 4) conductance.
                    >
                    > The resistance and inductance are in series with the
                    > load at the other end and the capacitance and
                    > conductance are in parallel with the load. What this
                    > means is that your transmission line will behave as a
                    > filter when a signal is passed along it. This has
                    > several side affects associated with it. I will
                    > discuss these in a moment. First let me digress into
                    > an aside about signals.
                    >
                    > According to Fourier, any real signal can be expressed
                    > as a sumation of an infinate combination of sines and
                    > cosines; each with a different frequency and
                    > amplitude. The frequencies of each "component" are
                    > integer multiples of the fundimental frequency. This
                    > is what people are refering to when they talk about
                    > n-th order harmonic frequencies (i.e. the third
                    > harmonic for example). In digital circuits, our
                    > transmission signal is a square wave. Transforming
                    > this into its Fourier series yeilds a combination of
                    > sine waves with odd-numbered multiples of the
                    > fundimental frequency. You don't really need to grasp
                    > this fully right now but it is revelant for your case.
                    >
                    > Getting back to the transmission line properties, let
                    > me remind you that a transmission line will behave as
                    > a passive filter when the line lengths get long
                    > enough. This results in two distinct effects on a
                    > signal that is being transmitted on it. 1) Phase
                    > shift 2) Voltage reflection.
                    >
                    > PHASE SHIFT -- All passive filters will create some
                    > sort of a phase shift of any AC signal that is passed
                    > through it. Whether or not the shift is positive or
                    > negative will depend upon the frequency of the signal
                    > and the type of filter it passes through. Recall that
                    > our digital square-wave is actually composed of an
                    > infinate combination of sine waves. When this type of
                    > wave is sent along a transmission line the wave can
                    > become "distorted" when it comes out the other end.
                    > This is because the "line filter" has shifted the
                    > phase of some of the square wave's harmonics. So what
                    > you should be looking for on the output end of your
                    > line will be ringing on your transitions and rounding
                    > of your signal edges. If your line is really long, or
                    > poorly constructed, you might even see something that
                    > looks more like an audio signal rather than a
                    > square-wave.
                    >
                    > VOLTAGE REFLECTION -- The second characteristic that
                    > must be accounted for is voltage reflection. What
                    > this describes is the fact that that not all power
                    > transmitted on the line will be transfered to the
                    > load. Some of it will be reflected back to the
                    > source. The effect is similar to the one observed
                    > when you take a string and tie one end to a wall and
                    > then take the other end and shake it up and down to
                    > create a wave on the string. When the wave reaches
                    > the wall, the wave "bounces back" towards you. This
                    > is onset by a mismatch in impedances between the
                    > source, transmission line, and load. When the voltage
                    > is reflected back to the source, if the source and
                    > line impedences don't match the wave will then be
                    > reflected back down to the load again. This results
                    > in what is called a "standing wave" and in "ideal"
                    > conditions can continue forever. One effect that can
                    > be caused by this standing wave is if the standing
                    > wave happens to be in phase with the signal at the
                    > load then the voltages add together. This can cause
                    > the voltage across the load to increase greatly. The
                    > same is true at the source. When the standing wave is
                    > in phase with the signal at the source, the voltage at
                    > the source can increase greatly.
                    >
                    > The opposite is also true. If the standing wave is
                    > 180 degrees out of phase with the signal and the
                    > relative amplitudes of each are similar, then the
                    > signal will in effect be canceled out at the load (or
                    > source depending on which end of the line you're on.)
                    > This is why impedence matching is so important between
                    > the source, line, and load. If the impedences match
                    > then a standing wave will not be seen. What you
                    > should look for to determine if this is happening is
                    > check your voltages. If you have a dramatic increase
                    > or decrease on either side of the line then you
                    > probably need to adjust the length of your line.
                    > Also, check each of the components on either side of
                    > the line. If they are getting hot then that probably
                    > indicates a problem as well.
                    >
                    > I forget the exact length, but I believe these effects
                    > start to become noticeable when the length of your
                    > line is 1/100th that of the signal wavelength but I'll
                    > have to look this up to be sure. At your voltages and
                    > frequencies, you will probably have to worry more
                    > about phase shift than voltage reflection but it never
                    > hurts to check for both. Also, the degree in which
                    > these effects are manifested depend upon the type of
                    > transmission line used.
                    >
                    > If you want more information on either the Fourier
                    > transform or transmission line properties do a google
                    > search. There is quite a bit of information out there
                    > on both topics.
                    >
                    > Hope this helps you find what you are looking for.
                    >
                    > Shawn
                    >
                    > http://www.geocities.com/sstandfast
                    >
                    > __________________________________________________
                    > Do You Yahoo!?
                    > Tired of spam? Yahoo! Mail has the best spam protection around
                    > http://mail.yahoo.com
                    >
                  • Robert Hedan
                    I have a suggestion: - try with a short wire, note results on scope. - try with a very long wire, compare results on scope with short wire results. If it
                    Message 9 of 16 , May 1, 2006
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                      I have a suggestion:

                      - try with a short wire, note results on scope.
                      - try with a very long wire, compare results on scope with short wire
                      results.

                      If it matches, hurray!

                      Robert
                      :)


                      > -----Message d'origine-----
                      > De : Electronics_101@yahoogroups.com
                      > [mailto:Electronics_101@yahoogroups.com] De la part de lcdpublishing
                      > Envoyé : mai 1 2006 10:48
                      > À : Electronics_101@yahoogroups.com
                      > Objet : [Electronics_101] Re: SPI interfacing - How long can
                      > external connections be?
                      >
                      >
                      > Roy, I will do when I get the cable in that I plan on using for
                      > this. By chance, can you give me a hint as to what sort of good and
                      > bad things I should be looking for?
                      >
                      > Right now, my technique on the scope is more or less, if I see two
                      > horizontal lines - spaced apart at the voltage and duration I think
                      > they should be - I am happy.
                      >
                      > Chris
                      >
                    • lcdpublishing
                      That is somewhat what I plan to do. However, if storage worked on my scope - this would all be much easier to see! I guess I could get a series of identical
                      Message 10 of 16 , May 1, 2006
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                        That is somewhat what I plan to do. However, if storage worked on
                        my scope - this would all be much easier to see! I guess I could
                        get a series of identical characters passing between the two chips.
                        I believe letter N was the one that adds up to 01010101 binary. If
                        I can get a repeating pattern it should be pretty easy to watch and
                        compare - I hope :-)

                        Chris


                        --- In Electronics_101@yahoogroups.com, Robert Hedan
                        <robert.hedan@...> wrote:
                        >
                        > I have a suggestion:
                        >
                        > - try with a short wire, note results on scope.
                        > - try with a very long wire, compare results on scope with short
                        wire
                        > results.
                        >
                        > If it matches, hurray!
                        >
                        > Robert
                        > :)
                        >
                        >
                        > > -----Message d'origine-----
                        > > De : Electronics_101@yahoogroups.com
                        > > [mailto:Electronics_101@yahoogroups.com] De la part de
                        lcdpublishing
                        > > Envoyé : mai 1 2006 10:48
                        > > À : Electronics_101@yahoogroups.com
                        > > Objet : [Electronics_101] Re: SPI interfacing - How long can
                        > > external connections be?
                        > >
                        > >
                        > > Roy, I will do when I get the cable in that I plan on using for
                        > > this. By chance, can you give me a hint as to what sort of good
                        and
                        > > bad things I should be looking for?
                        > >
                        > > Right now, my technique on the scope is more or less, if I see
                        two
                        > > horizontal lines - spaced apart at the voltage and duration I
                        think
                        > > they should be - I am happy.
                        > >
                        > > Chris
                        > >
                        >
                      • Robert Hedan
                        Chris, http://www.prepressure.com/library/binhex.htm Robert
                        Message 11 of 16 , May 1, 2006
                        • 0 Attachment
                          Chris,

                          http://www.prepressure.com/library/binhex.htm

                          Robert
                          :)


                          > -----Message d'origine-----
                          > De : Electronics_101@yahoogroups.com
                          > [mailto:Electronics_101@yahoogroups.com] De la part de lcdpublishing
                          > Envoyé : mai 1 2006 15:52
                          > À : Electronics_101@yahoogroups.com
                          > Objet : [Electronics_101] Re: SPI interfacing - How long can
                          > external connections be?
                          >
                          >
                          > That is somewhat what I plan to do. However, if storage worked on
                          > my scope - this would all be much easier to see! I guess I could
                          > get a series of identical characters passing between the two chips.
                          > I believe letter N was the one that adds up to 01010101 binary. If
                          > I can get a repeating pattern it should be pretty easy to watch and
                          > compare - I hope :-)
                          >
                          > Chris
                          >
                        • lcdpublishing
                          Thanks buddy! I was off by a couple - it s capital U Chris ... lcdpublishing ... on ... could ... chips. ... If ... and
                          Message 12 of 16 , May 1, 2006
                          • 0 Attachment
                            Thanks buddy! I was off by a couple - it's capital U

                            Chris



                            --- In Electronics_101@yahoogroups.com, Robert Hedan
                            <robert.hedan@...> wrote:
                            >
                            > Chris,
                            >
                            > http://www.prepressure.com/library/binhex.htm
                            >
                            > Robert
                            > :)
                            >
                            >
                            > > -----Message d'origine-----
                            > > De : Electronics_101@yahoogroups.com
                            > > [mailto:Electronics_101@yahoogroups.com] De la part de
                            lcdpublishing
                            > > Envoyé : mai 1 2006 15:52
                            > > À : Electronics_101@yahoogroups.com
                            > > Objet : [Electronics_101] Re: SPI interfacing - How long can
                            > > external connections be?
                            > >
                            > >
                            > > That is somewhat what I plan to do. However, if storage worked
                            on
                            > > my scope - this would all be much easier to see! I guess I
                            could
                            > > get a series of identical characters passing between the two
                            chips.
                            > > I believe letter N was the one that adds up to 01010101 binary.
                            If
                            > > I can get a repeating pattern it should be pretty easy to watch
                            and
                            > > compare - I hope :-)
                            > >
                            > > Chris
                            > >
                            >
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