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Thread: Teensy AREF? etape sensor?

  1. #1

    Teensy AREF? etape sensor?

    Hi I'm looking to hook up the miltone etape sensor:
    http://cdn.sparkfun.com/datasheets/S...C-8_040213.pdf

    They mention using a voltage divider. The example I found used pins 2 & 3 where pin 2 goes to gnd. pin 3 goes to one side of a 560 resistor and to analog input 0. the other side of the resistor goes to 3.3v and to aref.

    I was wondering what the equivalent of aref might be and if I wanted to use multiples of this sensor if someone could suggest a wiring configuration? sorry I'm rather new to all of this..

  2. #2
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    There is an Aref pin on the Teensy, but you would normally use the 3.3V -> resistor->ADCpin->eTape ->gnd (or aGnd if getting more careful)

    Aref is normally used as an input if you have a really precise voltage reference that you would feed the ADC via aref and your divider (normally from a special more $ component than the normal supply). For an initial setup don't bother, but it's one of the things to do if you want to reduce the noise
    https://www.arduino.cc/en/Reference/analogReference

  3. #3
    Quote Originally Posted by GremlinWrangler View Post
    There is an Aref pin on the Teensy, but you would normally use the 3.3V -> resistor->ADCpin->eTape ->gnd (or aGnd if getting more careful)

    Aref is normally used as an input if you have a really precise voltage reference that you would feed the ADC via aref and your divider (normally from a special more $ component than the normal supply). For an initial setup don't bother, but it's one of the things to do if you want to reduce the noise
    https://www.arduino.cc/en/Reference/analogReference

    Thank you for the explanation most appreciated!!

    Just got to get my teensy a little more reliable.. I'm having com port issues having to manually reset often to get it to upload.. but apart from that I really appreciate everyone whos taking time out to help us newbies!

  4. #4
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    Re needing to reset. Either your code is doing something exotic with clocks or interupts that disables USB (you are using the defualt speed?) or there maybe some sillyness on the PC side. A cold start may be a useful test point, as would be loading up a 'blink' and seeing if your code did actually load, just produced an error message in the loader.

  5. #5
    Senior Member Constantin's Avatar
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    AREF can be used with an analogReference(EXTERNAL) declaration for the AREF source to provide a more stable voltage, which in turn should produce more reproducible results. Pauls intent was the use of a voltage shunt diode, where the 470Ohm resistor provides a mA-level power source to AREF (see schematic).

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