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two stamps triggering same LED — Parallax Forums

two stamps triggering same LED

ArchiverArchiver Posts: 46,084
edited 2004-04-11 02:16 in General Discussion
I have two stamps. One was programmed by someone else, and the other
one has my code on it. I simply want my stamp to power a LED
occasionally. The LED is also connected to one of the output pins of
the other stamp.

So basically I have an output from each stamp connected to the same
LED. I know it would be bad if I drove one stamp pin high while the
other was trying to be low, but could I just put a 1n914 diode on
both of the stamp pins so there wouldn't be a problem?

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 00:31
    Not a good idea unless you put a diode on the other side as well.

    Stamp 1
    [noparse][[/noparse]>|
    +
    | LED
    *
    [noparse][[/noparse]>|
    \/\/\
    Vss
    |
    Stamp 2
    [noparse][[/noparse]>|
    +


    -- Jon Williams
    -- Parallax


    Original Message
    From: andy_watson5 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Vdj5107k26ya665hoTrvQwgzrSb086_KOESNG84gnR0nY0uIp-i8Z33YQw_om_kuHPHb3hHJ0ebCN6iZBLI]andywatson@m...[/url
    Sent: Tuesday, March 09, 2004 5:18 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] two stamps triggering same LED


    I have two stamps. One was programmed by someone else, and the other
    one has my code on it. I simply want my stamp to power a LED
    occasionally. The LED is also connected to one of the output pins of
    the other stamp.

    So basically I have an output from each stamp connected to the same
    LED. I know it would be bad if I drove one stamp pin high while the
    other was trying to be low, but could I just put a 1n914 diode on
    both of the stamp pins so there wouldn't be a problem?



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  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 00:32
    --- andy_watson5 <andywatson@m...> wrote:
    > I have two stamps. One was programmed by someone
    > else, and the other
    > one has my code on it. I simply want my stamp to
    > power a LED
    > occasionally. The LED is also connected to one of
    > the output pins of
    > the other stamp.

    So, Andy, you don't have a way to know which stamp is
    lighting the LED...Is that okay? Just curious.



    =====
    Chris Savage
    Knight Designs
    324 West Main Street
    Montour Falls, NY 14865
    (607) 535-6777

    http://www.knightdesigns.com

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  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 01:01
    Isn't this just a logical or? You can buy an or gate at radio shack for
    like 99 cents.

    On Tue, 9 Mar 2004, Jon Williams wrote:

    > Not a good idea unless you put a diode on the other side as well.
    >
    > Stamp 1
    [noparse][[/noparse]>|
    +
    > | LED
    > *
    [noparse][[/noparse]>|
    \/\/\
    Vss
    > |
    > Stamp 2
    [noparse][[/noparse]>|
    +
    >
    >
    > -- Jon Williams
    > -- Parallax
    >
    >
    >
    Original Message
    > From: andy_watson5 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=AKlT8n_r_AR9wgIEGVUNyuRKa54MkZsSYVEK30bCfwnfdX2cBjIJtuLFgkPlBhSq4ilw7VPeLdcQ]andywatson@m...[/url
    > Sent: Tuesday, March 09, 2004 5:18 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] two stamps triggering same LED
    >
    >
    > I have two stamps. One was programmed by someone else, and the other
    > one has my code on it. I simply want my stamp to power a LED
    > occasionally. The LED is also connected to one of the output pins of
    > the other stamp.
    >
    > So basically I have an output from each stamp connected to the same
    > LED. I know it would be bad if I drove one stamp pin high while the
    > other was trying to be low, but could I just put a 1n914 diode on
    > both of the stamp pins so there wouldn't be a problem?
    >
    >
    >
    > To UNSUBSCRIBE, just send mail to:
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    Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
    Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
    email: lamont@a... WWW: http://www.serv.net
    "Do not fear mistakes, There Are None" - Miles Davis
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 01:22
    Yes, I'm just performing a logical OR, but just for simplicity, I
    thought I'd try doing it with just diodes and save a little room on
    my already cramped circuit board.

    --- In basicstamps@yahoogroups.com, "Sean T. Lamont .lost."
    <lamont@a...> wrote:
    >
    > Isn't this just a logical or? You can buy an or gate at radio shack
    for
    > like 99 cents.
    >
    > On Tue, 9 Mar 2004, Jon Williams wrote:
    >
    > > Not a good idea unless you put a diode on the other side as well.
    > >
    > > Stamp 1
    [noparse][[/noparse]>|
    +
    > > | LED
    > > *
    [noparse][[/noparse]>|
    \/\/\
    Vss
    > > |
    > > Stamp 2
    [noparse][[/noparse]>|
    +
    > >
    > >
    > > -- Jon Williams
    > > -- Parallax
    > >
    > >
    > >
    Original Message
    > > From: andy_watson5 [noparse][[/noparse]mailto:andywatson@m...]
    > > Sent: Tuesday, March 09, 2004 5:18 PM
    > > To: basicstamps@yahoogroups.com
    > > Subject: [noparse][[/noparse]basicstamps] two stamps triggering same LED
    > >
    > >
    > > I have two stamps. One was programmed by someone else, and the
    other
    > > one has my code on it. I simply want my stamp to power a LED
    > > occasionally. The LED is also connected to one of the output
    pins of
    > > the other stamp.
    > >
    > > So basically I have an output from each stamp connected to the
    same
    > > LED. I know it would be bad if I drove one stamp pin high while
    the
    > > other was trying to be low, but could I just put a 1n914 diode on
    > > both of the stamp pins so there wouldn't be a problem?
    > >
    > >
    > >
    > > 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.
    > >
    > > Yahoo! Groups Links
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > > 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.
    > >
    > > Yahoo! Groups Links
    > >
    > >
    > >
    > >
    > >
    > >
    >
    > Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc.
    (ServNet)
    > Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma -
    Bremerton
    > email: lamont@a... WWW: http://www.serv.net
    > "Do not fear mistakes, There Are None" - Miles Davis
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 03:29
    First thing I'd worry about is driving and LED from a stamp pin period! The
    stamp cant really handle that much current from a single pin. Should switcvh
    a transistor and power the led from the seperate 5v supply.


    >
    Original Message
    > From: andy_watson5 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=AUiGQb-UCEGvRAyuXzTwWLmxd9YFtHfxSK0fGHygoPKwI5WbBYtNcJBvwyVCN7jlLQFJUNnTjDf31w]andywatson@m...[/url
    > Sent: March 9, 2004 3:18 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] two stamps triggering same LED
    >
    >
    > I have two stamps. One was programmed by someone else, and the other
    > one has my code on it. I simply want my stamp to power a LED
    > occasionally. The LED is also connected to one of the output pins of
    > the other stamp.
    >
    > So basically I have an output from each stamp connected to the same
    > LED. I know it would be bad if I drove one stamp pin high while the
    > other was trying to be low, but could I just put a 1n914 diode on
    > both of the stamp pins so there wouldn't be a problem?
    >
    >
    >
    > 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.
    >
    > Yahoo! Groups Links
    >
    >
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 04:27
    Where are you getting that idea? Puhleeze (excuse my incredulity) ...
    we drive LEDs all the time right out of the BASIC Stamp. A typical LED
    only requires about 5 mA or so to light nicely. The only thing one
    needs to be cautious of is driving too many LEDs from on IO group.

    -- Jon Williams
    -- Parallax



    Original Message
    From: PatM [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=B5_MGST_Vtsf2vJfqLSZtm0MBhZVXsqlpDiepNm-P3s05U_4kvVOxW91VxmskWLyOfzH_BFc0w]pmeloy@s...[/url
    Sent: Tuesday, March 09, 2004 9:29 PM
    To: basicstamps@yahoogroups.com
    Subject: RE: [noparse][[/noparse]basicstamps] two stamps triggering same LED


    First thing I'd worry about is driving and LED from a stamp pin period!
    The stamp cant really handle that much current from a single pin. Should
    switcvh a transistor and power the led from the seperate 5v supply.


    >
    Original Message
    > From: andy_watson5 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=OZ60X5w5OG16alBMuj8IP8voRmhwRFMbnZ4KW_o4CYnDb-rP3gf1d8DxCo3ymrlp6cQ4BBAX6k-5IA]andywatson@m...[/url
    > Sent: March 9, 2004 3:18 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] two stamps triggering same LED
    >
    >
    > I have two stamps. One was programmed by someone else, and the other
    > one has my code on it. I simply want my stamp to power a LED
    > occasionally. The LED is also connected to one of the output pins of
    > the other stamp.
    >
    > So basically I have an output from each stamp connected to the same
    > LED. I know it would be bad if I drove one stamp pin high while the
    > other was trying to be low, but could I just put a 1n914 diode on both

    > of the stamp pins so there wouldn't be a problem?
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 13:36
    Diode OR the drive to the pins together.

    Connect the output pin of each stamp to the cathode of any standard
    rectifier diode, a 1N4003 would do fine.
    Connect the anode ends of the two rectifiers together.
    Connect the anode ends also to the LED.
    Connect the other end of the LED to the current limiting resistor. If it's
    a 5 Volt system, and the LED is a 20 mA unit, then 300 Ohm is what I use.
    Connect the other end of the current limiting resistor to +5 Volts.

    With this connection, the LED will be illuminated when either of the two
    stamps pulls the correct pin low.



    >
    Original Message
    > From: andy_watson5 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=DLnAek2b42z7DHBkw0dWlNRqgoLsWHH0y2SNHL620tPKzI-8nvjSrzPCz5z61d3zxchEm2CLDUzR5QZ-]andywatson@m...[/url
    > Sent: March 9, 2004 3:18 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] two stamps triggering same LED
    >
    >
    > I have two stamps. One was programmed by someone else, and the other
    > one has my code on it. I simply want my stamp to power a LED
    > occasionally. The LED is also connected to one of the output pins of
    > the other stamp.
    >
    > So basically I have an output from each stamp connected to the same
    > LED. I know it would be bad if I drove one stamp pin high while the
    > other was trying to be low, but could I just put a 1n914 diode on both

    > of the stamp pins so there wouldn't be a problem?


    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.

    Yahoo! Groups Links
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 16:22
    Hmm, I must have been thinking multiple LEDs or something. I did some work
    with 7 segment displays a long while back - maybe thats why I was thinking
    of the stamp not being able to handle the current.

    Senility creeping up!

    >
    Original Message
    > From: Jon Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=adwckNf8nPCT381z1biVqZ2EBM2BUiMS3GTklT2u3lYvzAvbyWrmpUClpggE8CK1KQCWh2zBaAsaW2eBrObL2g]jwilliams@p...[/url
    > Sent: March 9, 2004 8:27 PM
    > To: basicstamps@yahoogroups.com
    > Subject: RE: [noparse][[/noparse]basicstamps] two stamps triggering same LED
    >
    >
    > Where are you getting that idea? Puhleeze (excuse my incredulity) ...
    > we drive LEDs all the time right out of the BASIC Stamp. A typical LED
    > only requires about 5 mA or so to light nicely. The only thing one
    > needs to be cautious of is driving too many LEDs from on IO group.
    >
    > -- Jon Williams
    > -- Parallax
    >
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-10 16:33
    Yes, when lighting multiple LEDs (as with a 7-segment display) we must
    be aware and control current. I typically use a 470 ohm current limiter
    for LEDs when it's up to a few, but for a 7-segment display I bump the
    current limiters up to 1K to protect the BASIC Stamp.

    I hope I did come on too strong ... may I suggest that we all be careful
    about what the BASIC Stamp CAN'T do without checking [noparse][[/noparse]the docs]
    carefully as there are lots of youngsters and newcomers that will take
    our word as gospel.

    -- Jon Williams
    -- Parallax

    Original Message
    From: PatM [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=pkT8K7DvZLA9FdllLljGKQsSR7y5LwMmeqYBZVTbA79R8kFSzgCYMw0_WKOeG0JiaJOfbHeL]pmeloy@s...[/url
    Sent: Wednesday, March 10, 2004 10:23 AM
    To: basicstamps@yahoogroups.com
    Subject: RE: [noparse][[/noparse]basicstamps] two stamps triggering same LED


    Hmm, I must have been thinking multiple LEDs or something. I did some
    work with 7 segment displays a long while back - maybe thats why I was
    thinking of the stamp not being able to handle the current.

    Senility creeping up!

    >
    Original Message
    > From: Jon Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=og1pgeuQ2KcxS0uP4-_6X00lGJe5DOz_itg7s0mN-9DHy9-gH5Q-K20ke7HewS4ZKBBrA_1epVICc8JV2Q]jwilliams@p...[/url
    > Sent: March 9, 2004 8:27 PM
    > To: basicstamps@yahoogroups.com
    > Subject: RE: [noparse][[/noparse]basicstamps] two stamps triggering same LED
    >
    >
    > Where are you getting that idea? Puhleeze (excuse my incredulity) ...

    > we drive LEDs all the time right out of the BASIC Stamp. A typical
    > LED only requires about 5 mA or so to light nicely. The only thing
    > one needs to be cautious of is driving too many LEDs from on IO group.
    >
    > -- Jon Williams
    > -- Parallax
  • ArchiverArchiver Posts: 46,084
    edited 2004-04-11 02:16
    BS2 Pe Attendance project. I am wondering if there is a way to write a
    program to accept two different signals and log it at the same exact
    time. Example I am trying to keep track of my employees when they
    arrive to work with there id badges being swiped in the office reader.
    It should store the first track that consist of their first and last
    name and also at the same time log their employee number that is on the
    second line and store it. Could this be possible? If so could someone
    give me a example of doing different task at the same time? Please?

    Original Message
    From: Jon Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=iWV_J_BWm9myr5oLrBGndzlYKC3Yp9FD3L3AW7XaNsSNsouLZ_G8NGbjCcQA2Cx3e2LdQrWnK3Fd9yaLCw]jwilliams@p...[/url
    Sent: Wednesday, March 10, 2004 10:34 AM
    To: basicstamps@yahoogroups.com
    Subject: RE: [noparse][[/noparse]basicstamps] two stamps triggering same LED

    Yes, when lighting multiple LEDs (as with a 7-segment display) we must
    be aware and control current. I typically use a 470 ohm current limiter
    for LEDs when it's up to a few, but for a 7-segment display I bump the
    current limiters up to 1K to protect the BASIC Stamp.

    I hope I did come on too strong ... may I suggest that we all be careful
    about what the BASIC Stamp CAN'T do without checking [noparse][[/noparse]the docs]
    carefully as there are lots of youngsters and newcomers that will take
    our word as gospel.

    -- Jon Williams
    -- Parallax

    Original Message
    From: PatM [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=v3ZIsHdiPRn87MNdCT9KjlHZSPA-G2yT5wQwS4AEAokDKBaIg4wjd2xsn14WtPKp53Km-lg]pmeloy@s...[/url
    Sent: Wednesday, March 10, 2004 10:23 AM
    To: basicstamps@yahoogroups.com
    Subject: RE: [noparse][[/noparse]basicstamps] two stamps triggering same LED


    Hmm, I must have been thinking multiple LEDs or something. I did some
    work with 7 segment displays a long while back - maybe thats why I was
    thinking of the stamp not being able to handle the current.

    Senility creeping up!

    >
    Original Message
    > From: Jon Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=iWV_J_BWm9myr5oLrBGndzlYKC3Yp9FD3L3AW7XaNsSNsouLZ_G8NGbjCcQA2Cx3e2LdQrWnK3Fd9yaLCw]jwilliams@p...[/url
    > Sent: March 9, 2004 8:27 PM
    > To: basicstamps@yahoogroups.com
    > Subject: RE: [noparse][[/noparse]basicstamps] two stamps triggering same LED
    >
    >
    > Where are you getting that idea? Puhleeze (excuse my incredulity) ...

    > we drive LEDs all the time right out of the BASIC Stamp. A typical
    > LED only requires about 5 mA or so to light nicely. The only thing
    > one needs to be cautious of is driving too many LEDs from on IO group.
    >
    > -- Jon Williams
    > -- Parallax


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