stamp killing power to itself (clarified)
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Posts: 46,084
Chris-
Here's one way to approach this problem. Consider that you have two
states. Let's define state A as the Stamp being without power.
Let's define state B as the Stamp being connected to power. Let's
also define two logical variables: accessory (accessory power
present) and powerdown (a Stamp output level).
While in state A, you transition to state B only when the accessory
line is high. While in state B, you transition to state A only when
the Stamp asserts powerdown. Transistions from A to B ignore the
Stamp's powerdown level, and transistions from B to A ignore the
accessory level. OK so far?
While in state A, detecting a high on the accessory line is pretty
straightforward.
To control the Stamp's powerdown assertion while in state B, I'd
connect a Stamp I/O pin (the source of the powerdown output) to the
Stamp's power source through a ~4.7K pullup resistor. When power is
(re)applied to the Stamp, the pin is high because all pins assume an
input state upon powerup until your program directs otherwise. When
your Stamp decides it's time time to turn itself off, it can make the
pin a low output. That's your powerdown assertion that gets you back
to state A.
Now to implement this logical model, lets's say that a relay is open
while in state A, and closed while in state B. The relay switches
power to your Stamp (maybe a switching transistor would be
better--perhaps others can make a suggestion). The relay's
coil/transistor's base would be enabled if in state A and the
accessory line goes high, and disabled if in state B and the Stamp's
powerdown output goes low. You'd need some logic gates or other
external hardware to complete the hardware implementation and control
the relay/transistor. Seems like it oughta work.
Regards,
Steve
On 25 Mar 01 at 1:08, christopher bergeron wrote:
> To clarify my last statement: I want the shutdown to
> actually run a routine. Therefore the "clarified"
> pseduocode is:
>
> Main:
> do a bunch
> of stuff here
> Loop:
> if button1 = 1 then Shutdown
> if button2 = 1 then blahblah
> goto Loop
>
> Shutdown:
> send "XXX" to serial port
> pause 2000
> ??? <
what to do here???
>
Here's one way to approach this problem. Consider that you have two
states. Let's define state A as the Stamp being without power.
Let's define state B as the Stamp being connected to power. Let's
also define two logical variables: accessory (accessory power
present) and powerdown (a Stamp output level).
While in state A, you transition to state B only when the accessory
line is high. While in state B, you transition to state A only when
the Stamp asserts powerdown. Transistions from A to B ignore the
Stamp's powerdown level, and transistions from B to A ignore the
accessory level. OK so far?
While in state A, detecting a high on the accessory line is pretty
straightforward.
To control the Stamp's powerdown assertion while in state B, I'd
connect a Stamp I/O pin (the source of the powerdown output) to the
Stamp's power source through a ~4.7K pullup resistor. When power is
(re)applied to the Stamp, the pin is high because all pins assume an
input state upon powerup until your program directs otherwise. When
your Stamp decides it's time time to turn itself off, it can make the
pin a low output. That's your powerdown assertion that gets you back
to state A.
Now to implement this logical model, lets's say that a relay is open
while in state A, and closed while in state B. The relay switches
power to your Stamp (maybe a switching transistor would be
better--perhaps others can make a suggestion). The relay's
coil/transistor's base would be enabled if in state A and the
accessory line goes high, and disabled if in state B and the Stamp's
powerdown output goes low. You'd need some logic gates or other
external hardware to complete the hardware implementation and control
the relay/transistor. Seems like it oughta work.
Regards,
Steve
On 25 Mar 01 at 1:08, christopher bergeron wrote:
> To clarify my last statement: I want the shutdown to
> actually run a routine. Therefore the "clarified"
> pseduocode is:
>
> Main:
> do a bunch
> of stuff here
> Loop:
> if button1 = 1 then Shutdown
> if button2 = 1 then blahblah
> goto Loop
>
> Shutdown:
> send "XXX" to serial port
> pause 2000
> ??? <
what to do here???
>
Comments
actually run a routine. Therefore the "clarified"
pseduocode is:
Main:
do a bunch
of stuff here
Loop:
if button1 = 1 then Shutdown
if button2 = 1 then blahblah
goto Loop
Shutdown:
send "XXX" to serial port
pause 2000
??? <
what to do here???
blahblah:
debug "blahblah",cr
I'm trying to kill power to the stamp so that when
it's next started it will begin at the top (Main[noparse]:)[/noparse].
So when power gets cut, the stamp will tell everyone
he's getting ready to shut down; they will do what
they need to, and it will turn off (GET turned off).
That is the goal. I'm just not quite sure what the
outcome is going to be when I kill the power to the
stamp (via a transistor/relay combo) _using the
stamp_. The only reason I'm concerned is that it's
[noparse][[/noparse]relatively] odd to take the power out from under
something that is causing the "take power out" to
occur. Does this make any sense or have I had too
much to drink? Perhaps both?
At any rate -
If I send a BS2 pin high to trigger a relay that kills
power to the stamp, will it osscilate or something
wierd, or will it do what I expect?
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>actually run a routine. Therefore the "clarified"
>pseduocode is:
>
>Main:
*SNIP*
>I'm trying to kill power to the stamp so that when
>it's next started it will begin at the top (Main[noparse]:)[/noparse].
>
You will need a relay that is controlled by the Stamp to
supply power to the Stamp through its contacts. You
will also need a pushbutton or switch in parallel with
the relay contacts to get the Stamp to start. Then the
first line in the program should be one to energise the
relay so that you can let go of the button.
Original Message
From: <carl@g...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, March 25, 2001 4:12 AM
Subject: Re: [noparse][[/noparse]basicstamps] stamp killing power to itself (clarified)
>>SNIP<<
>
> You will need a relay that is controlled by the Stamp to
> supply power to the Stamp through its contacts. You
> will also need a pushbutton or switch in parallel with
> the relay contacts to get the Stamp to start. Then the
> first line in the program should be one to energise the
> relay so that you can let go of the button.
>
I was thinking about the stamp driving a relay also, but there are two
relays. One is to turn itself off. To restart it, a start button is
pressed. The relay that turns it on has a set of contacts that holds itself
on, and to turn it off, that holding circuit is interrupted. Those who are
familiar with industrial controls or ladder logic will recognize this as a
basic start/stop control.
relay or FET power off so that the source of power to the
stamp goes to 1 volt or less [noparse][[/noparse]capacitors discharge in power
supply etc.] or if you make it so that the FET feeding power
to the stamp can only be on when the stamp has power - i.e.
to start the stamp you have to bypass the FET which switches
power to the stamp and then the stamp sets a pin high to hold
it's own power on. When this stamp pin goes off so does the
FET feeding the power to the stamp and the whole thing dies
until reset.
This type of thing is done all the time - consider when you
open a clothes dryer door and then have to push a button
to start again when the door is shut... :-)
> Date: Sun, 25 Mar 2001 01:08:53 -0800 (PST)
> From: christopher bergeron <christopher_bergeron@y...>
>To clarify my last statement: I want the shutdown to
>actually run a routine. Therefore the "clarified"
>pseduocode is:
>Main:
>do a bunch
>of stuff here
> Loop:
> if button1 = 1 then Shutdown
> if button2 = 1 then blahblah
> goto Loop
>Shutdown:
> send "XXX" to serial port
> pause 2000
> ??? <
what to do here???
What you do here is turn OFF the pin which is holding the
power to the stamp ON. Then the ON set needs to be
long enough for this pin to be set high to hold on.
>I'm trying to kill power to the stamp so that when
>it's next started it will begin at the top (Main[noparse]:)[/noparse].
You might do better to just put in a RESET pulse to the
stamp: [noparse][[/noparse]ground pin mclr #28 DIP] To assure it resets -
otherwise you rely on the start reset circuitry to work.
Empiricism rules - why don't you try something? :-)
If it oscillates it will be interesting debugging it...
Have fun... premena
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the stamp shuts itself off, it can't turn itself back on again.
just use the car's accessory line to drive a relay or anything like that to
control power to the stamp. Its simple, saves an IO line, and the stamp
can be turned back on easy.
-Rob
Original Message
From: "s premena" <premzee@j...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, March 25, 2001 9:40 PM
Subject: [noparse][[/noparse]basicstamps] RE:stamp killing power to itself (clarified)
> There should be no problem if you put in enough delay in the
> relay or FET power off so that the source of power to the
> stamp goes to 1 volt or less [noparse][[/noparse]capacitors discharge in power
> supply etc.] or if you make it so that the FET feeding power
> to the stamp can only be on when the stamp has power - i.e.
> to start the stamp you have to bypass the FET which switches
> power to the stamp and then the stamp sets a pin high to hold
> it's own power on. When this stamp pin goes off so does the
> FET feeding the power to the stamp and the whole thing dies
> until reset.
>
> This type of thing is done all the time - consider when you
> open a clothes dryer door and then have to push a button
> to start again when the door is shut... :-)
>
> > Date: Sun, 25 Mar 2001 01:08:53 -0800 (PST)
> > From: christopher bergeron <christopher_bergeron@y...>
>
>
> >To clarify my last statement: I want the shutdown to
> >actually run a routine. Therefore the "clarified"
> >pseduocode is:
>
> >Main:
> >do a bunch
> >of stuff here
> > Loop:
> > if button1 = 1 then Shutdown
> > if button2 = 1 then blahblah
> > goto Loop
>
> >Shutdown:
> > send "XXX" to serial port
> > pause 2000
> > ??? <
what to do here???
>
> What you do here is turn OFF the pin which is holding the
> power to the stamp ON. Then the ON set needs to be
> long enough for this pin to be set high to hold on.
>
> >I'm trying to kill power to the stamp so that when
> >it's next started it will begin at the top (Main[noparse]:)[/noparse].
>
> You might do better to just put in a RESET pulse to the
> stamp: [noparse][[/noparse]ground pin mclr #28 DIP] To assure it resets -
> otherwise you rely on the start reset circuitry to work.
>
> Empiricism rules - why don't you try something? :-)
> If it oscillates it will be interesting debugging it...
>
> Have fun... premena
>
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draws current thru one coil, which sets the relay contacts in one direction,
and thus switches on power to the circuit. The Stamp can draw current thru
the other coil, which sets the relay contacts in the other direction, which
switches off the power. Voil