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Anemometer output — Parallax Forums

Anemometer output

JAGJAG Posts: 2
in BASIC Stamp
Hello Guys,

I am the new kid on the block.
Have an Met One Anemometer 034B model.

I need to reed pulse count in and need analog voltage out.

Has anybody done this before?

Kind Regards,

JAG


Comments

  • Mike GreenMike Green Posts: 23,101
    The Basic Stamp can only do one thing at a time, so you have to go back and forth between functions. In your case, this means that you'll measure the pulse rate using the COUNT statement for some period of time, then generate a voltage using the PWM statement for some period of time. The amount of time for the COUNT statement depends on the frequency of the pulses and the wind speed range you want to deal with. You'll probably need some kind of voltage buffer for the output voltage since the Stamp will charge a capacitor and the charge will leak away over time while the Stamp looks at the anemometer pulses.

    If this sort of back and forth won't work for you, you could use an external DAC (Digital to Analog Converter) to generate the analog voltage so the Stamp can spend most of its time measuring the anemometer pulses and just update the DAC input register occasionally. Look in this text for information on this topic.
  • JAGJAG Posts: 2
    Thanks Mike, :)

    Cheers,
  • Tracy AllenTracy Allen Posts: 6,662
    Jag, do you mean to ask about reading both the pulse output of the reed switch for wind speed and also the analog voltage from the wind direction potentiometer? Mike inferred a different question from your wording.

    The Stamp can COUNT the pulses for a time interval, then read the analog value of the potentiometer. It is possible to read the value of the potentiometer using the RCTIME command, or by adding an external analog to digital converter. From those two values you find speed and direction.
  • ercoerco Posts: 20,256
    edited 2015-11-12 17:41
    Welcome to the forums, JAG. http://www.campbellsci.com/034b

    An analog solution would be to have the reed relay trigger a 555 one-shot, charging an electrolytic capacitor. The cap's (analog) voltage would increase as the RPM & pulse rate went up. For instance:

    http://www.diyelectronicsprojects.com/2012/08/frequency-to-voltage-converter-circuit-diagram.html
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