Loading ...
Sorry, an error occurred while loading the content.

Re: [LinkStation_General] Restart on Power Failure?!

Expand Messages
  • Schelte Bron
    ... I don t have the impression you can create sparks with a 100uF capacitor charged to 3.3V, so I don t think this is a big problem. On the other hand I
    Message 1 of 14 , Jan 3, 2006
    • 0 Attachment
      On Tuesday 03 January 2006 01:25, Derek Taubert wrote:
      > Interesting. A few concerns:
      >
      > 1) When the power button is pressed, the capacitor will drain
      > directly to ground through the switch contacts. That's going
      > to be quite a zap from a 100uF cap. At minimum, I would
      > suggest putting a resistor in series with the cap (something
      > several times less resistive than whatever the weak pullup to
      > 3.3V is) and then using a smaller cap.
      >
      I don't have the impression you can create sparks with a 100uF
      capacitor charged to 3.3V, so I don't think this is a big
      problem. On the other hand I wonder if it will still work with
      a smaller cap with a resistor in series. Anyway, the switch is
      not going to be used much after this modification. The LS will
      boot when the power is applied and will be shutdown with the
      shutdown command.

      > 2) Applying voltage (the charged cap) to an IC input after
      > device power is removed is a great way to cause latchup and
      > permanent damage over time. Have you looked closely at this
      > trace to determine what devices are connected to it?
      >
      Good point. I haven't checked what kind of circuitry the switch
      is connected to. I assumed it would be some part of the power
      supply. That should be able to handle a 3.3V reverse voltage,
      but I'm not sure. Should a diode in series with the cap not be
      able to prevent this reverse voltage? The disadvantage would be
      that the cap may take a longer time to discharge.

      > I would advise against using this particular mod as is. A
      > better design would duplicate the switch behavior (0 ohms vs.
      > Meg ohms) rather than the resulting voltage on the pin (0V
      > vs. 3.3V).
      >
      Thanks for sharing your concerns.


      Schelte.
    • Schelte Bron
      ... I am interested. ... Mine has at least survived a couple of cycles :-) Schelte.
      Message 2 of 14 , Jan 3, 2006
      • 0 Attachment
        On Tuesday 03 January 2006 19:41, James Stewart wrote:
        > > 2) Applying voltage (the charged cap) to an IC input after
        > > device power is removed is a great way to cause latchup and
        > > permanent damage over time. Have you looked closely at
        > > this trace to determine what devices are connected to it?
        >
        > Yes, it would be nice to see what this is controlling. My
        > guess would be a CMOS switch, but it could be a bipolar
        > transistor.
        >
        > > I would advise against using this particular mod as is. A
        > > better design would duplicate the switch behavior (0 ohms
        > > vs. Meg ohms) rather than the resulting voltage on the pin
        > > (0V vs. 3.3V).
        >
        > Okay, you could but the charging capacitor in front of a
        > transistor that is bridged across the switch. A little more
        > complicated, but safer. I could draw up a simple schematic
        > if there is interest.
        >
        I am interested.

        > Of couse if no one has blown up their LS with the circuit
        > as-is, then that might speak for itself.
        >
        Mine has at least survived a couple of cycles :-)


        Schelte.
      • KeepIt SimpleStupid
        Power on resets in general are a PITA. A good control element to use for push buttons etc. is a LED/FET like the VACTEC VTL5C1. It s a nice package with
        Message 3 of 14 , Jan 3, 2006
        • 0 Attachment
          Power on resets in general are a PITA. A good control
          element to use for push buttons etc. is a LED/FET like
          the VACTEC VTL5C1. It's a nice package with leads in
          and leads out.

          Other FET/LED DIP packages are available from
          www.digikey.com.

          RC circuits with a schmidt trigger are the de-facto
          standard for power-on reset, but they are not
          reliable.

          I designed a really good circuit for a car, but the
          timer part doesn't exist anymore (obsoleted by
          manufacturer). 0-10 sec, very fast reset, probably
          less than 10 mS.

          The hardest part is to get good reset once the timer
          has timed out.

          I'd try a delay on make timer from SSAC combined with
          the vactrol p/n. For giggles, I'd add an LM334 and a
          diode for polarity protection. When you do this you
          get a polarity protected 3-30V DC capable 2-wire
          isolated line that needs 10 mA that you can pretty
          much do anything with.

          What you need to do, is discharge the timing element
          when the device is off (no an easy feat) and discharge
          the timing element after it's been used for timing as
          well. Again, not necessarily an easy feat.

          That CAP thing is the primary reason many devices
          don't work after a brief power failure. It takes
          $10-$15 to do it right.
          I also learned the hard way, that it depands on how
          fast the power supply powers up.

          In a microprocessor based system I worked on, if I
          used a linear supply the standard RC and gate didn't
          work. If I used a switching supply, it worked. When
          I changed to a schmidt trigger, they both worked.

          Most timers, including commercial have very crummy
          reset times on the order of 100mS. Now you know why
          they say: unplug, wait 1 minute and plug back in.
          It's probably the reason it's not in the LS - cost!



          __________________________________________
          Yahoo! DSL – Something to write home about.
          Just $16.99/mo. or less.
          dsl.yahoo.com
        • Schelte Bron
          ... I would really like to keep it simple, so how about a cap and a resistor in parallel connected to ground on one side and the other side connected via a
          Message 4 of 14 , Jan 5, 2006
          • 0 Attachment
            On Tuesday 03 January 2006 01:25, Derek Taubert wrote:
            > 1) When the power button is pressed, the capacitor will drain
            > directly to ground through the switch contacts. That's going
            > to be quite a zap from a 100uF cap. At minimum, I would
            > suggest putting a resistor in series with the cap (something
            > several times less resistive than whatever the weak pullup to
            > 3.3V is) and then using a smaller cap.
            >
            > 2) Applying voltage (the charged cap) to an IC input after
            > device power is removed is a great way to cause latchup and
            > permanent damage over time. Have you looked closely at this
            > trace to determine what devices are connected to it?
            >
            I would really like to keep it simple, so how about a cap and a
            resistor in parallel connected to ground on one side and the
            other side connected via a diode to the on/off button signal?

            The diode will prevent any current flowing back into the LS
            circuitry. The cap will only be able to discharge through the
            resistor. That should take care of both concerns you raised.

            I have done some experiments and it works on my LS with a 6k8
            resistor and a 22uF cap. The LS reboots if the power has been
            disconnected for as little as 3 seconds.

            Do you see any more problems with this design?

            Actually, in my experiments I found that I could get all the
            functionality I need by just shorting the switch completely.
            The LS would boot when power is applied and I could shut it
            down with the shutdown command. It doesn't seem to shutdown or
            reboot automatically at other times. I expect the disk sleep
            function will also still work. Of course the on/off button is
            completely disabled in this situation.


            Schelte.
          • KeepIt SimpleStupid
            Not knowing exactly what the LS has you can try something like wire oring. Lets try some ascii art. ***************** Ground ! ! ! ! !
            Message 5 of 14 , Jan 5, 2006
            • 0 Attachment
              Not knowing exactly what the LS has you can try
              something like wire oring.

              Lets try some ascii art.

              ***************** Ground
              ! !
              ! !
              ! !
              ****** *****
              / \ / \
              ! !
              cap switch
              ! !
              ******************** To whatever needs reseting
              by a contact closure to ground

              This way either one of the signals can be interpreted
              as a
              keypress. It's just that power-up reset is
              unreliable.
              Add your resistor if you care. I'm assuming that the
              LS uses a contact closure to ground, but it doesn't
              have to be.
              PS: It's drawn upside down.

              What chip/pin is the power switch going to. Is it
              connected to anything else like a pull up or pull down
              resistor?


              --- Schelte Bron <sbron@...> wrote:

              > On Tuesday 03 January 2006 01:25, Derek Taubert
              > wrote:
              > > 1) When the power button is pressed, the capacitor
              > will drain
              > > directly to ground through the switch contacts.
              > That's going
              > > to be quite a zap from a 100uF cap. At minimum, I
              > would
              > > suggest putting a resistor in series with the cap
              > (something
              > > several times less resistive than whatever the
              > weak pullup to
              > > 3.3V is) and then using a smaller cap.
              > >
              > > 2) Applying voltage (the charged cap) to an IC
              > input after
              > > device power is removed is a great way to cause
              > latchup and
              > > permanent damage over time. Have you looked
              > closely at this
              > > trace to determine what devices are connected to
              > it?
              > >
              > I would really like to keep it simple, so how about
              > a cap and a
              > resistor in parallel connected to ground on one side
              > and the
              > other side connected via a diode to the on/off
              > button signal?
              >
              > The diode will prevent any current flowing back into
              > the LS
              > circuitry. The cap will only be able to discharge
              > through the
              > resistor. That should take care of both concerns you
              > raised.
              >
              > I have done some experiments and it works on my LS
              > with a 6k8
              > resistor and a 22uF cap. The LS reboots if the power
              > has been
              > disconnected for as little as 3 seconds.
              >
              > Do you see any more problems with this design?
              >
              > Actually, in my experiments I found that I could get
              > all the
              > functionality I need by just shorting the switch
              > completely.
              > The LS would boot when power is applied and I could
              > shut it
              > down with the shutdown command. It doesn't seem to
              > shutdown or
              > reboot automatically at other times. I expect the
              > disk sleep
              > function will also still work. Of course the on/off
              > button is
              > completely disabled in this situation.
              >
              >
              > Schelte.
              >




              __________________________________________
              Yahoo! DSL – Something to write home about.
              Just $16.99/mo. or less.
              dsl.yahoo.com
            • Schelte Bron
              ... The ascii picture is a bit hard to make out, but that looks exactly like the setup I used and described on the wiki. With my more complicated proposal I m
              Message 6 of 14 , Jan 6, 2006
              • 0 Attachment
                On Friday 06 January 2006 05:48, KeepIt SimpleStupid wrote:
                > Not knowing exactly what the LS has you can try
                > something like wire oring.
                >
                The ascii picture is a bit hard to make out, but that looks
                exactly like the setup I used and described on the wiki. With
                my more complicated proposal I'm trying to address the concerns
                some people raised about that first setup.

                > Add your resistor if you care. I'm assuming that the
                > LS uses a contact closure to ground, but it doesn't
                > have to be.
                >
                > What chip/pin is the power switch going to. Is it
                > connected to anything else like a pull up or pull down
                > resistor?
                >
                The LS indeed uses a contact closure to ground. I haven't been
                able to determine where the signal is going to. I lost track of
                the circuit board trace when it disappeared under the IDE
                connector. From my measurements it appears like the signal is
                pulled up with a resistance of around 7K.


                Schelte.
              • KeepIt SimpleStupid
                ... Try this on for size: Disconnect the switch from the non ground side. Label the switch point (b) and the circuit board side point (b). Connect the anodes
                Message 7 of 14 , Jan 6, 2006
                • 0 Attachment
                  --- Schelte Bron <sbron@...> wrote:

                  > On Friday 06 January 2006 05:48, KeepIt SimpleStupid
                  > wrote:
                  > > Not knowing exactly what the LS has you can try
                  > > something like wire oring.
                  > >
                  > The ascii picture is a bit hard to make out, but
                  > that looks
                  > exactly like the setup I used and described on the
                  > wiki. With
                  > my more complicated proposal I'm trying to address
                  > the concerns
                  > some people raised about that first setup.
                  >
                  > > Add your resistor if you care. I'm assuming that
                  > the
                  > > LS uses a contact closure to ground, but it
                  > doesn't
                  > > have to be.
                  > >
                  > > What chip/pin is the power switch going to. Is it
                  > > connected to anything else like a pull up or pull
                  > down
                  > > resistor?
                  > >
                  > The LS indeed uses a contact closure to ground. I
                  > haven't been
                  > able to determine where the signal is going to. I
                  > lost track of
                  > the circuit board trace when it disappeared under
                  > the IDE
                  > connector. From my measurements it appears like the
                  > signal is
                  > pulled up with a resistance of around 7K.
                  >
                  >
                  > Schelte.


                  Try this on for size:

                  Disconnect the switch from the non ground side. Label
                  the switch point (b) and the circuit board side point
                  (b).

                  Connect the anodes of two 1n4001 diodes together and
                  connect to point (b).

                  Connect the cathode of one of the diodes to point (a).

                  Connect the cathode of the other to your cap and the
                  negative of the cap to ground.

                  In this case the diodes create isolation and there is
                  no issue of a cap across the switch.

                  If you cannot unsolder both ends of the switch, then
                  go to plan (b).

                  Obtain p/n CNC1H001CT-ND from www.digi-key.com.
                  Connect pins 4 and 6 across the switch. Polarity
                  doesn't matter.

                  Make R=(Vcc-1.2)/10mA. Vcc could be 3.3, 5 or even
                  12V and pull this resistor to this voltage. Connect
                  the other end of this resistor to pin #1 and a cap
                  from pin 2 to ground observing polarity. Make 5 * R *
                  C about equal to (0.1 to 0.5 where R is in ohms, and C
                  is in Farads.

                  KISS








                  __________________________________________
                  Yahoo! DSL – Something to write home about.
                  Just $16.99/mo. or less.
                  dsl.yahoo.com
                • KeepIt SimpleStupid
                  I was a little hasty before I replied. There is a problem with both designs. The reset time would be really bad because the charge on the capacitor would not
                  Message 8 of 14 , Jan 6, 2006
                  • 0 Attachment
                    I was a little hasty before I replied. There is a
                    problem with both designs. The reset time would be
                    really bad because the charge on the capacitor would
                    not drain. I'd suggest a starting value of a parallel
                    resistor of ten times the value of R used.

                    KISS

                    --- KeepIt SimpleStupid <keepitsimplestupid@...>
                    wrote:

                    >
                    >
                    > --- Schelte Bron <sbron@...> wrote:
                    >
                    > > On Friday 06 January 2006 05:48, KeepIt
                    > SimpleStupid
                    > > wrote:
                    > > > Not knowing exactly what the LS has you can try
                    > > > something like wire oring.
                    > > >
                    > > The ascii picture is a bit hard to make out, but
                    > > that looks
                    > > exactly like the setup I used and described on the
                    > > wiki. With
                    > > my more complicated proposal I'm trying to address
                    > > the concerns
                    > > some people raised about that first setup.
                    > >
                    > > > Add your resistor if you care. I'm assuming
                    > that
                    > > the
                    > > > LS uses a contact closure to ground, but it
                    > > doesn't
                    > > > have to be.
                    > > >
                    > > > What chip/pin is the power switch going to. Is
                    > it
                    > > > connected to anything else like a pull up or
                    > pull
                    > > down
                    > > > resistor?
                    > > >
                    > > The LS indeed uses a contact closure to ground. I
                    > > haven't been
                    > > able to determine where the signal is going to. I
                    > > lost track of
                    > > the circuit board trace when it disappeared under
                    > > the IDE
                    > > connector. From my measurements it appears like
                    > the
                    > > signal is
                    > > pulled up with a resistance of around 7K.
                    > >
                    > >
                    > > Schelte.
                    >
                    >
                    > Try this on for size:
                    >
                    > Disconnect the switch from the non ground side.
                    > Label
                    > the switch point (b) and the circuit board side
                    > point
                    > (b).
                    >
                    > Connect the anodes of two 1n4001 diodes together and
                    > connect to point (b).
                    >
                    > Connect the cathode of one of the diodes to point
                    > (a).
                    >
                    > Connect the cathode of the other to your cap and the
                    > negative of the cap to ground.
                    >
                    > In this case the diodes create isolation and there
                    > is
                    > no issue of a cap across the switch.
                    >
                    > If you cannot unsolder both ends of the switch, then
                    > go to plan (b).
                    >
                    > Obtain p/n CNC1H001CT-ND from www.digi-key.com.
                    > Connect pins 4 and 6 across the switch. Polarity
                    > doesn't matter.
                    >
                    > Make R=(Vcc-1.2)/10mA. Vcc could be 3.3, 5 or even
                    > 12V and pull this resistor to this voltage. Connect
                    > the other end of this resistor to pin #1 and a cap
                    > from pin 2 to ground observing polarity. Make 5 * R
                    > *
                    > C about equal to (0.1 to 0.5 where R is in ohms, and
                    > C
                    > is in Farads.
                    >
                    > KISS
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    > __________________________________________
                    > Yahoo! DSL � Something to write home about.
                    > Just $16.99/mo. or less.
                    > dsl.yahoo.com
                    >
                    >




                    __________________________________________
                    Yahoo! DSL – Something to write home about.
                    Just $16.99/mo. or less.
                    dsl.yahoo.com
                  • Schelte Bron
                    ... Thanks for thinking along with me, but I think there s a slight miscommunication. The setup I proposed works, is about as simple as it gets and has a
                    Message 9 of 14 , Jan 7, 2006
                    • 0 Attachment
                      On Saturday 07 January 2006 00:11, KeepIt SimpleStupid wrote:
                      > Try this on for size:
                      >
                      > Disconnect the switch from the non ground side. Label
                      > the switch point (b) and the circuit board side point
                      > (b).
                      >
                      > Connect the anodes of two 1n4001 diodes together and
                      > connect to point (b).
                      >
                      > Connect the cathode of one of the diodes to point (a).
                      >
                      > Connect the cathode of the other to your cap and the
                      > negative of the cap to ground.
                      >
                      > In this case the diodes create isolation and there is
                      > no issue of a cap across the switch.
                      >
                      > If you cannot unsolder both ends of the switch, then
                      > go to plan (b).
                      >
                      > Obtain p/n CNC1H001CT-ND from www.digi-key.com.
                      > Connect pins 4 and 6 across the switch. Polarity
                      > doesn't matter.
                      >
                      > Make R=(Vcc-1.2)/10mA. Vcc could be 3.3, 5 or even
                      > 12V and pull this resistor to this voltage. Connect
                      > the other end of this resistor to pin #1 and a cap
                      > from pin 2 to ground observing polarity. Make 5 * R *
                      > C about equal to (0.1 to 0.5 where R is in ohms, and C
                      > is in Farads.
                      >
                      Thanks for thinking along with me, but I think there's a slight
                      miscommunication. The setup I proposed works, is about as
                      simple as it gets and has a reasonable reset time (3 seconds).
                      My only question was if anyone sees any problems with that
                      design.

                      If you look at the picture I included in the wiki article you
                      will see that your plan A is not going to work because
                      unsoldering the switch cannot be done without a big risk of
                      damaging the LS.

                      Your plan B doesn't sound simpler than my proposal and I don't
                      see how it could work. The part number you mentioned is a 16
                      pin SMD 4-port opto-isolator and you seem to be using pins from
                      different ports. I assume you meant something like p/n H11F1-ND
                      or similar, but then the circuit is still more complicated than
                      mine and I don't see any advantages.

                      So unless you can point me to any dangers for the LS using my
                      setup, I'm going to go with that.


                      Thanks,
                      Schelte.
                    • KeepIt SimpleStupid
                      ... Your correct with the part number that you selected. So one cap, 1 IC and 2 resistors you should have something that works and keeps the functionality of
                      Message 10 of 14 , Jan 7, 2006
                      • 0 Attachment
                        --- Schelte Bron <sbron@...> wrote:

                        > On Saturday 07 January 2006 00:11, KeepIt
                        > SimpleStupid wrote:
                        > > Try this on for size:
                        > >
                        > > Disconnect the switch from the non ground side.
                        > Label
                        > > the switch point (b) and the circuit board side
                        > point
                        > > (b).
                        > >
                        > > Connect the anodes of two 1n4001 diodes together
                        > and
                        > > connect to point (b).
                        > >
                        > > Connect the cathode of one of the diodes to point
                        > (a).
                        > >
                        > > Connect the cathode of the other to your cap and
                        > the
                        > > negative of the cap to ground.
                        > >
                        > > In this case the diodes create isolation and there
                        > is
                        > > no issue of a cap across the switch.
                        > >
                        > > If you cannot unsolder both ends of the switch,
                        > then
                        > > go to plan (b).
                        > >
                        > > Obtain p/n CNC1H001CT-ND from www.digi-key.com.
                        > > Connect pins 4 and 6 across the switch. Polarity
                        > > doesn't matter.
                        > >
                        > > Make R=(Vcc-1.2)/10mA. Vcc could be 3.3, 5 or
                        > even
                        > > 12V and pull this resistor to this voltage.
                        > Connect
                        > > the other end of this resistor to pin #1 and a cap
                        > > from pin 2 to ground observing polarity. Make 5 *
                        > R *
                        > > C about equal to (0.1 to 0.5 where R is in ohms,
                        > and C
                        > > is in Farads.
                        > >
                        > Thanks for thinking along with me, but I think
                        > there's a slight
                        > miscommunication. The setup I proposed works, is
                        > about as
                        > simple as it gets and has a reasonable reset time (3
                        > seconds).
                        > My only question was if anyone sees any problems
                        > with that
                        > design.
                        >
                        > If you look at the picture I included in the wiki
                        > article you
                        > will see that your plan A is not going to work
                        > because
                        > unsoldering the switch cannot be done without a big
                        > risk of
                        > damaging the LS.
                        >
                        > Your plan B doesn't sound simpler than my proposal
                        > and I don't
                        > see how it could work. The part number you mentioned
                        > is a 16
                        > pin SMD 4-port opto-isolator and you seem to be
                        > using pins from
                        > different ports. I assume you meant something like
                        > p/n H11F1-ND
                        > or similar, but then the circuit is still more
                        > complicated than
                        > mine and I don't see any advantages.
                        >
                        > So unless you can point me to any dangers for the LS
                        > using my
                        > setup, I'm going to go with that.

                        Your correct with the part number that you selected.
                        So one cap, 1 IC and 2 resistors you should have
                        something that works and keeps the functionality of
                        the button.

                        Many years ago, like 20, I used this technique to turn
                        off an audio processor when the AMP turned off. I
                        also had the ability to turn the audio system on via
                        the processors remote, Still works.
                        Weird switches (Dedicated off)
                        ON (one push -20 db, 2nd push 0 db)
                        Since the circuitry was external, isolation was
                        important,

                        Thanks for catching the errors.

                        KISS
                        >
                        >
                        > Thanks,
                        > Schelte.
                        >




                        __________________________________________
                        Yahoo! DSL – Something to write home about.
                        Just $16.99/mo. or less.
                        dsl.yahoo.com
                      Your message has been successfully submitted and would be delivered to recipients shortly.