i/o pins shorted to ground
Archiver
Posts: 46,084
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
(internally).
1. what can cause this?
2. will putting a pull down resistor e.g. 10kOhm prevent the problem?
thanks
paul
Comments
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
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
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:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Z2rNLlmplA1rw7WAraNNCt2C1DkMb0xAvuRhMy2Fu4mLgJJPx4oNeKQm3OsKmA8KLUF30m5sYXCb]pjw24@c...[/url
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:
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This is a good thing. The resistor I was talking
about is 'in series', in other words 'in the
signal path', in other words:
BS2Pin_A ----/\/\/\/\
BS2Pin_B
This series resistor should be 220 ohms, to
limit the 'contention current', when
BS2Pin_A is an output, driven HIGH, and
BS2Pin_B is an OUTPUT, driven LOW. You
see, you then have two drivers, both
struggling to control the state of
the line. (Note this is not a normal
state of affairs, but it could happen
accidentally)
BS2Pin_A will act as a current SOURCE,
outputting current into the resistor.
BS2Pin_B will act as a current SINK,
sucking current through the resistor.
With the resistor there, they are
limited to (5 Volts / 220 ohms == 22 mA)
22 milliamps, which is within the
current limit of the Stamp. Without
the resistor there, they try to put
out (5 volts / .01 ohms == 500 AMPS)
a LOT of current. Of course, they
can't put out that much current, but
the attempt WILL burn out the drivers
behind one of the pins if they are
allowed to try long enough.
--- In basicstamps@yahoogroups.com, "justforgoyourmove" <pjw24@c...>
wrote:
> 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
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:
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> and Body of the message will be ignored.
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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:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=z2KTC73rhJDLn1BGkoKfJ62h6QxcPwTuY6uexmV8jWh4sgCy0RbRRVMZYz0Jk-7gbMV5Z4CeJXknijo]pjw24@c...[/url
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...
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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...
resistor.
-- Jon Williams
-- Parallax
Original Message
From: justforgoyourmove [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=noHcPwkA8HHnMC1-b69KYnmnDjo1nEThqbMrBT8D4DEbV1wnCHbRGAGtW8PBKS8MJIsk1GvgZwyq33Y]pjw24@c...[/url
Sent: Wednesday, August 06, 2003 5:13 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: i/o pins shorted to ground
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
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and Body of the message will be ignored.
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This message has been scanned by WebShield. Please report SPAM to
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