i/o pins shorted to ground(better ascii art)
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Posts: 46,084
this is actually the situation - you see the input could either be
serin/serout information or possibly 10 VDC. Would the voltage
divider with the top 10k resistor between the pin and the input
allow the serial communication to work - and/or would this work:
serin/serout (but possibly 10 VDC)
|
|
+---[noparse][[/noparse]470]----<Stamp Pin
|
|
[noparse][[/noparse]10k]
|
|
Vss
or would this again be a voltage divider that would screw up the
serial communication - i.e. would not let logic high be 5 but rather
470/10470 * 5??
thanks again
paul
--- In basicstamps@yahoogroups.com, "justforgoyourmove" <pjw24@c...>
wrote:
> this is actually the situation - you see the input could either be
> serin/serout information or possibly 10 VDC. Would the voltage
> divider with the top 10k resistor between the pin and the input
> allow the serial communication to work - and/or would this work
>
> Stamp Pin >
[noparse][[/noparse]470]----+
serin/serout (but possibly 10
VDC)
> |
> |
> [noparse][[/noparse]10k]
> |
> |
> Vss
>
> ???
> or would this again be a voltage divider that would screw up the
> serial communication - i.e. would not let logic high be 5 but
rather
> 470/10470 * 5??
>
> thanks again
>
> paul
> --- In basicstamps@yahoogroups.com, "Jon Williams"
<jwilliams@p...>
> wrote:
> > I would suggest using a voltage divider to make the input Stamp-
> safe.
> > Like this:
> >
> > 10v
> > |
> > |
> > o |
> > |-
> > o |
> > |
> > |
> > [noparse][[/noparse]10K]
> > |
> > |
> > Stamp Pin >
*
> > |
> > |
> > [noparse][[/noparse]10K]
> > |
> > |
> > Vss
> >
> > Now when the button is pressed, the Stamp will see 5V. The 220
is
> no
> > longer necessary as the path to 10v or to ground (Vss) is
through
> 10K.
> >
> > -- Jon Williams
> > -- Parallax
> >
> >
Original Message
> > From: justforgoyourmove [noparse][[/noparse]mailto[noparse]:p[/noparse]jw24@c...]
> > Sent: Wednesday, August 06, 2003 3:29 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: i/o pins shorted to ground
> >
> >
> > thanks you - so likewise if the button were to short the pin to
> say
> > 10 VDC rather than the 5 VDC that Vdd is would a 470 ohm
resistor
> do
> > the trick? (10V/470ohm = 21mAmps)
> >
> > thanks again
> >
> > paul
> > --- In basicstamps@yahoogroups.com, "Jon Williams"
> <jwilliams@p...>
> > wrote:
> > > No, 10K will not cause any problems as a pull-down; it's a
> standard
> > > value. What Allan was pointing out is that if one of your
> inputs
> > > becomes an output low and you press a button, you'll have a
> direct
> > short
> > > and can damage a pin. His recommendation for an inline 220 ohm
> > resistor
> > > on the pin is good advice and cheap insurance.
> > >
> > > Vdd
> > > |
> > > |
> > > o |
> > > |-
> > > o |
> > > |
> > > Stamp Pin >
[noparse][[/noparse]220]
*
> > > |
> > > |
> > > [noparse][[/noparse]10K]
> > > |
> > > |
> > > Vss
> > >
> > >
> > > -- Jon Williams
> > > -- Parallax
> > >
> > >
> > >
Original Message
> > > From: justforgoyourmove [noparse][[/noparse]mailto[noparse]:p[/noparse]jw24@c...]
> > > Sent: Tuesday, August 05, 2003 4:10 PM
> > > To: basicstamps@yahoogroups.com
> > > Subject: [noparse][[/noparse]basicstamps] Re: i/o pins shorted to ground
> > >
> > >
> > > i am using a 10kOhm resistor right now because it also serves
as
> a
> > > pull down resistor as in the one shown for serin serout
> > > communications on page 290 of the "Basic Stamp Manual version
> 2.0"
> > >
> > > Will this value for the resistor ohm cause any trouble?
> > >
> > > thanks again
> > >
> > > paul
> > >
> > >
> > > --- In basicstamps@yahoogroups.com, "Allan Lane"
> <allan.lane@h...>
> > > wrote:
> > > > I'm not sure, but perhaps overcurrent on the pin?
> > > > This can be caused by tying two outputs together
> > > > with no resistance between them, driving one high,
> > > > and the other low.
> > > >
> > > > Putting a 220 ohm resistor between the two drivers
> > > > will keep damage from happening -- it limits the
> > > > current to what the pins will bear. Of course,
> > > > it won't repair existing damage...
> > > >
> > > > --- In basicstamps@yahoogroups.com, "justforgoyourmove"
> > > <pjw24@c...>
> > > > wrote:
> > > > > it seems some of my i/o pins have been shorted to ground
> > > > > (internally).
> > > > >
> > > > > 1. what can cause this?
> > > > > 2. will putting a pull down resistor e.g. 10kOhm prevent
the
> > > > problem?
> > > > >
> > > > > thanks
> > > > >
> > > > > paul
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > basicstamps-unsubscribe@yahoogroups.com
> > > from the same email address that you subscribed. Text in the
> > Subject
> > > and Body of the message will be ignored.
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> > > http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> > >
> > > This message has been scanned by WebShield. Please report SPAM
> to
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> >
> >
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> > from the same email address that you subscribed. Text in the
> Subject
> > and Body of the message will be ignored.
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> >
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> > abuse@p...
serin/serout information or possibly 10 VDC. Would the voltage
divider with the top 10k resistor between the pin and the input
allow the serial communication to work - and/or would this work:
serin/serout (but possibly 10 VDC)
|
|
+---[noparse][[/noparse]470]----<Stamp Pin
|
|
[noparse][[/noparse]10k]
|
|
Vss
or would this again be a voltage divider that would screw up the
serial communication - i.e. would not let logic high be 5 but rather
470/10470 * 5??
thanks again
paul
--- In basicstamps@yahoogroups.com, "justforgoyourmove" <pjw24@c...>
wrote:
> this is actually the situation - you see the input could either be
> serin/serout information or possibly 10 VDC. Would the voltage
> divider with the top 10k resistor between the pin and the input
> allow the serial communication to work - and/or would this work
>
> Stamp Pin >
[noparse][[/noparse]470]----+
serin/serout (but possibly 10
VDC)
> |
> |
> [noparse][[/noparse]10k]
> |
> |
> Vss
>
> ???
> or would this again be a voltage divider that would screw up the
> serial communication - i.e. would not let logic high be 5 but
rather
> 470/10470 * 5??
>
> thanks again
>
> paul
> --- In basicstamps@yahoogroups.com, "Jon Williams"
<jwilliams@p...>
> wrote:
> > I would suggest using a voltage divider to make the input Stamp-
> safe.
> > Like this:
> >
> > 10v
> > |
> > |
> > o |
> > |-
> > o |
> > |
> > |
> > [noparse][[/noparse]10K]
> > |
> > |
> > Stamp Pin >
*
> > |
> > |
> > [noparse][[/noparse]10K]
> > |
> > |
> > Vss
> >
> > Now when the button is pressed, the Stamp will see 5V. The 220
is
> no
> > longer necessary as the path to 10v or to ground (Vss) is
through
> 10K.
> >
> > -- Jon Williams
> > -- Parallax
> >
> >
Original Message
> > From: justforgoyourmove [noparse][[/noparse]mailto[noparse]:p[/noparse]jw24@c...]
> > Sent: Wednesday, August 06, 2003 3:29 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: i/o pins shorted to ground
> >
> >
> > thanks you - so likewise if the button were to short the pin to
> say
> > 10 VDC rather than the 5 VDC that Vdd is would a 470 ohm
resistor
> do
> > the trick? (10V/470ohm = 21mAmps)
> >
> > thanks again
> >
> > paul
> > --- In basicstamps@yahoogroups.com, "Jon Williams"
> <jwilliams@p...>
> > wrote:
> > > No, 10K will not cause any problems as a pull-down; it's a
> standard
> > > value. What Allan was pointing out is that if one of your
> inputs
> > > becomes an output low and you press a button, you'll have a
> direct
> > short
> > > and can damage a pin. His recommendation for an inline 220 ohm
> > resistor
> > > on the pin is good advice and cheap insurance.
> > >
> > > Vdd
> > > |
> > > |
> > > o |
> > > |-
> > > o |
> > > |
> > > Stamp Pin >
[noparse][[/noparse]220]
*
> > > |
> > > |
> > > [noparse][[/noparse]10K]
> > > |
> > > |
> > > Vss
> > >
> > >
> > > -- Jon Williams
> > > -- Parallax
> > >
> > >
> > >
Original Message
> > > From: justforgoyourmove [noparse][[/noparse]mailto[noparse]:p[/noparse]jw24@c...]
> > > Sent: Tuesday, August 05, 2003 4:10 PM
> > > To: basicstamps@yahoogroups.com
> > > Subject: [noparse][[/noparse]basicstamps] Re: i/o pins shorted to ground
> > >
> > >
> > > i am using a 10kOhm resistor right now because it also serves
as
> a
> > > pull down resistor as in the one shown for serin serout
> > > communications on page 290 of the "Basic Stamp Manual version
> 2.0"
> > >
> > > Will this value for the resistor ohm cause any trouble?
> > >
> > > thanks again
> > >
> > > paul
> > >
> > >
> > > --- In basicstamps@yahoogroups.com, "Allan Lane"
> <allan.lane@h...>
> > > wrote:
> > > > I'm not sure, but perhaps overcurrent on the pin?
> > > > This can be caused by tying two outputs together
> > > > with no resistance between them, driving one high,
> > > > and the other low.
> > > >
> > > > Putting a 220 ohm resistor between the two drivers
> > > > will keep damage from happening -- it limits the
> > > > current to what the pins will bear. Of course,
> > > > it won't repair existing damage...
> > > >
> > > > --- In basicstamps@yahoogroups.com, "justforgoyourmove"
> > > <pjw24@c...>
> > > > wrote:
> > > > > it seems some of my i/o pins have been shorted to ground
> > > > > (internally).
> > > > >
> > > > > 1. what can cause this?
> > > > > 2. will putting a pull down resistor e.g. 10kOhm prevent
the
> > > > problem?
> > > > >
> > > > > thanks
> > > > >
> > > > > paul
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > basicstamps-unsubscribe@yahoogroups.com
> > > from the same email address that you subscribed. Text in the
> > Subject
> > > and Body of the message will be ignored.
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> > > http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> > >
> > > This message has been scanned by WebShield. Please report SPAM
> to
> > > abuse@p...
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
> Subject
> > and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
> > This message has been scanned by WebShield. Please report SPAM to
> > abuse@p...