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How to detect an on/off switch — Parallax Forums

How to detect an on/off switch

ArchiverArchiver Posts: 46,084
edited 2004-05-13 16:21 in General Discussion
Hi Everyone,

What's the simplest way for my PC to detect (through a Basic Stamp
2SX) changes in an on/off switch? I have pushbuttons down, but I
need my PC to know when there is a change of state. I have four
switches. Thanks!

-Josh

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-05-12 17:14
    Josh,

    There is a great tutorial on same in free Parallax downloadable
    books.

    Also, you didn't indicate what TYPE of switch. Are you trying to
    detect the on/off of an appliance (i.e. 110VAC) or the on/off of a
    pushbutton?

    In the case of the latter, see the below referenced book (free
    download) on detecting the state of a pushbutton and subsequently
    illuminating an LED.

    Ref: What's a Microcomputer, pg 80, Chap 3, Activity 3
    "Pushbutton Control of an LED Circuit"

    http://www.parallax.com/dl/docs/books/edu/wamv2_1.pdf

    --- In basicstamps@yahoogroups.com, "Josh Polk" <mcstampfunk3@y...>
    wrote:
    > Hi Everyone,
    >
    > What's the simplest way for my PC to detect (through a Basic Stamp
    > 2SX) changes in an on/off switch? I have pushbuttons down, but I
    > need my PC to know when there is a change of state. I have four
    > switches. Thanks!
    >
    > -Josh
  • ArchiverArchiver Posts: 46,084
    edited 2004-05-12 19:05
    Another thought, See Nuts & Volts Issue #6 on how to switch a
    transistor / relay. Or am I missing the point completely :-)

    http://www.parallax.com/dl/docs/cols/nv/vol1/col/nv6.pdf

    --- In basicstamps@yahoogroups.com, "Josh Polk" <mcstampfunk3@y...>
    wrote:
    > Hi Everyone,
    >
    > What's the simplest way for my PC to detect (through a Basic Stamp
    > 2SX) changes in an on/off switch? I have pushbuttons down, but I
    > need my PC to know when there is a change of state. I have four
    > switches. Thanks!
    >
    > -Josh
  • ArchiverArchiver Posts: 46,084
    edited 2004-05-13 02:12
    That's not what I'm trying to do. Basically I have four on/off
    light switches that I'm connecting to the Stamp as inputs. When I
    flip the switch from on to off I need the Stamp to know it. I guess
    I can just read the state of the pins in a loop... maybe it's
    simpler than I thought. I'll figure something out.

    --- In basicstamps@yahoogroups.com, "johncouture" <basicstamp@j...>
    wrote:
    > Another thought, See Nuts & Volts Issue #6 on how to switch a
    > transistor / relay. Or am I missing the point completely :-)
    >
    > http://www.parallax.com/dl/docs/cols/nv/vol1/col/nv6.pdf
    >
    > --- In basicstamps@yahoogroups.com, "Josh Polk"
    <mcstampfunk3@y...>
    > wrote:
    > > Hi Everyone,
    > >
    > > What's the simplest way for my PC to detect (through a Basic
    Stamp
    > > 2SX) changes in an on/off switch? I have pushbuttons down, but
    I
    > > need my PC to know when there is a change of state. I have four
    > > switches. Thanks!
    > >
    > > -Josh
  • ArchiverArchiver Posts: 46,084
    edited 2004-05-13 15:25
    What else is the Stamp doing that you're so concerned with the time
    required to check four switches?

    It can be done with discrete logic (gates, flip-flops, etc.) but this
    seems to be overkill for what you seem to want to do. If timing is
    really a problem, set up the code to only check once every so often
    (for example, once for every ten passes through the "main" loop).

    Russ

    --- In basicstamps@yahoogroups.com, "Josh Polk" <mcstampfunk3@y...> wrote:
    >
    > That's not what I'm trying to do. Basically I have four on/off
    > light switches that I'm connecting to the Stamp as inputs. When I
    > flip the switch from on to off I need the Stamp to know it. I guess
    > I can just read the state of the pins in a loop... maybe it's
    > simpler than I thought. I'll figure something out.
    >
    > --- In basicstamps@yahoogroups.com, "johncouture" <basicstamp@j...>
    > wrote:
    > > Another thought, See Nuts & Volts Issue #6 on how to switch a
    > > transistor / relay. Or am I missing the point completely :-)
    > >
    > > http://www.parallax.com/dl/docs/cols/nv/vol1/col/nv6.pdf
    > >
    > > --- In basicstamps@yahoogroups.com, "Josh Polk"
    > <mcstampfunk3@y...>
    > > wrote:
    > > > Hi Everyone,
    > > >
    > > > What's the simplest way for my PC to detect (through a Basic
    > Stamp
    > > > 2SX) changes in an on/off switch? I have pushbuttons down, but
    > I
    > > > need my PC to know when there is a change of state. I have four
    > > > switches. Thanks!
    > > >
    > > > -Josh
  • ArchiverArchiver Posts: 46,084
    edited 2004-05-13 15:30
    Why not read all switches at once into a NIBBLE?

    MainLoop:
    OldNibble = Nibble
    Nibble = INA
    If OldNibble <> Nibble then ChangeOfState
    goto MainLoop

    ChangeOfState:
    (Do something here)
    goto MainLoop



    >What else is the Stamp doing that you're so concerned with the time
    >required to check four switches?
    >
    >It can be done with discrete logic (gates, flip-flops, etc.) but this
    >seems to be overkill for what you seem to want to do. If timing is
    >really a problem, set up the code to only check once every so often
    >(for example, once for every ten passes through the "main" loop).
    >
    >Russ
    >
    >--- In basicstamps@yahoogroups.com, "Josh Polk" <mcstampfunk3@y...> wrote:
    > >
    > > That's not what I'm trying to do. Basically I have four on/off
    > > light switches that I'm connecting to the Stamp as inputs. When I
    > > flip the switch from on to off I need the Stamp to know it. I guess
    > > I can just read the state of the pins in a loop... maybe it's
    > > simpler than I thought. I'll figure something out.
    > >
    > > --- In basicstamps@yahoogroups.com, "johncouture" <basicstamp@j...>
    > > wrote:
    > > > Another thought, See Nuts & Volts Issue #6 on how to switch a
    > > > transistor / relay. Or am I missing the point completely :-)
    > > >
    > > > http://www.parallax.com/dl/docs/cols/nv/vol1/col/nv6.pdf
    > > >
    > > > --- In basicstamps@yahoogroups.com, "Josh Polk"
    > > <mcstampfunk3@y...>
    > > > wrote:
    > > > > Hi Everyone,
    > > > >
    > > > > What's the simplest way for my PC to detect (through a Basic
    > > Stamp
    > > > > 2SX) changes in an on/off switch? I have pushbuttons down, but
    > > I
    > > > > need my PC to know when there is a change of state. I have four
    > > > > switches. Thanks!
    > > > >
    > > > > -Josh
    >
    >
    >
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  • ArchiverArchiver Posts: 46,084
    edited 2004-05-13 16:21
    This is a simple program.

    'put pullup resistors (4.7K) on ports 1 to 4
    'set stamp version
    'define any variables

    loop:
    low 5 'resets the outputs to off condition
    low 6
    low 7 'etc.

    if in1 = 0 then relay1 'check state of pushbutton 1
    if in2 = 0 then relay2 'etc.
    if in3 = 0 then relay3 'etc.
    in in4 = 0 then relay4 'etc.
    goto loop 'if no buttons are pressed, look again

    relay1:
    high 5 'output port 5 to trigger transistor/relay
    'if you want relay to stay ln a while, insert pause here
    'or jump to a subroutine for a delay
    return

    relay2:
    high 6 'etc.
    return

    relay3:
    high 7 'etc
    return
    etc.
    etc.
    check out this web site for schematics/hardware to drive relays, valves,
    motors, etc.
    jim http://www.geocities.com/jimforkin2003/

    Original Message
    From: johncouture [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=foXaz-jFeWX3Nv0_p7WNnCnO1kVqbPrSQ9hExeiUWBGI28ZpbYdCCrasIgdPrOZG-ZewHt8UCOsJ9iP23oox]basicstamp@j...[/url
    Sent: Wednesday, May 12, 2004 2:06 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Re: How to detect an on/off switch


    Another thought, See Nuts & Volts Issue #6 on how to switch a
    transistor / relay. Or am I missing the point completely :-)

    http://www.parallax.com/dl/docs/cols/nv/vol1/col/nv6.pdf

    --- In basicstamps@yahoogroups.com, "Josh Polk" <mcstampfunk3@y...>
    wrote:
    > Hi Everyone,
    >
    > What's the simplest way for my PC to detect (through a Basic Stamp
    > 2SX) changes in an on/off switch? I have pushbuttons down, but I
    > need my PC to know when there is a change of state. I have four
    > switches. Thanks!
    >
    > -Josh




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