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1.7Volt signal and the SX28 — Parallax Forums

1.7Volt signal and the SX28

$WMc%$WMc% Posts: 1,884
edited 2009-03-11 01:06 in General Discussion
Hello All

I'm trying to read a 1.7volt clock/DATA pulse with the SX28
The pulses are from a watch battery powered device @ 77kHz

I know I need to amp. the signal up to TTL levels.

What I'm after is a AMP or DRIVER to do this?

I have looked @ the MN13811 ~ MPF102

If anyone has some knowledge of a usable circuit to do this.Something simple,·I would greatly App. It.

Thanks in Advance!


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Comments

  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2009-03-05 02:18
    Have you tried setting a pin to TTL mode?
    TTL mode has threshold of 1.4V whereas CMOS mode (default)
    has threshold 50% of VDD.
    1.7V signal may be able to trigger a pin in TTL mode.

    regards peter
  • BeanBean Posts: 8,129
    edited 2009-03-05 03:10
    Peter,
    TTL mode IS the default threshold level.
    So you shouldn't have any problem detecting a 1.7V singnal.

    Bean.

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    ·
  • RS_JimRS_Jim Posts: 1,771
    edited 2009-03-05 04:58
    Hi,

    Another way you could be sure and detect the 1.7 volts is set up the analog comparitor on B2 and B3 with a reference voltage of say 1 volt.· When the pulse you are trying to detect is below 1 volt B0 is low and when the pulse you are detecting goes above 1 volt, B0 goes hi.
  • $WMc%$WMc% Posts: 1,884
    edited 2009-03-06 01:16
    Thanks Guys

    Learned:
    1:TTL/CMOS mode. cool!
    2:Comparator-Port B. way cool! 'just what I needed; But I don't know how to write this in the new SX/B templates?

    I have found the templates very different from what I'm use too, But I want to give them a try and learn some new stuff.

    If anyone has a link or A SX/B template program that uses the comparator. I would greatly APP. it


    ____Major_RadioShack_Parallax__Shopper_____$WMc%_____________

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  • BeanBean Posts: 8,129
    edited 2009-03-06 01:25
    Look in the help file...


    attachment.php?attachmentid=59115

    Bean.

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    SXB Help Comparitor.jpg
    1440 x 900 - 164K
  • $WMc%$WMc% Posts: 1,884
    edited 2009-03-06 01:40
    Bean

    You Are the MAN !!!!!!!!!!!!!


    _____________$WMc%______________

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    The Truth is out there············································ BoogerWoods, FL. USA
  • $WMc%$WMc% Posts: 1,884
    edited 2009-03-07 01:57
    Bean

    I have found a BUG with Vista and XP64; In the "help" topic window.

    I felt pretty stupid after You posted the "help option" for a question That I asked.

    I rechecked the help file and found nothing on "Analog Comparator" and the selection (explore window) I had did not match
    what You posted.

    I reloaded SX-Key v3.2.92.h on My XP64 machine and know I have the same selection (explore window) that was is in Your post reply.

    I tired this with My Vista laptop and I still have the older (explore window). with the help topic?

    I did notice that You had SX-Key v3.2.92.j running, Is this a fix for the Bug?

    I can,t thank You enough for the Screen Shot. with out it I would have never known what I was missing.

    ____________$WMc%_____________

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    The Truth is out there············································ BoogerWoods, FL. USA
  • PJMontyPJMonty Posts: 983
    edited 2009-03-10 00:06
    $WMc%,

    Can you post a screenshot of the problem under Vista?

    Thanks,
    PeterM
  • $WMc%$WMc% Posts: 1,884
    edited 2009-03-11 01:06
    PJMonty

    Sorry But I had fixed the problem on My Vista machine before I caught Your post reply.

    I ran the problem down to SpyBot. I couldn't believe all the apps. it was blocking.

    I'm not sure if this is a Windows app. or what, But I got rid of it. Now all is well!.

    ___________$WMc%________

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