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Soil Moisture sensor , Zigbee project

Discussion in 'Sensors and Actuators' started by Nayana, Jan 20, 2016.

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  1. Nayana

    Nayana

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    0
    Jan 20, 2016
    In a project I am doing, I have to send analog readings of a soil moisture sensor through zigbee. I have connected the sensor Vcc to 5v and ground; the zigbee Vcc to 3.3v and ground. The analog pin of sensor to Txx pin of adapter on which the zigbee is mounter. On the coordinator zigbee, i/o packets are being recieved..but it is always giving value of "020a" or "020b" irrespective of the data from sensor. I have also fed the analog data of sensor through voltage divider to keep it within 1.2v range..can you suggest what I am doing wrong??
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,538
    1,967
    Nov 17, 2011
    The Txx pin of the Zigbee adapter very probably requires a digital signal (a data stream), not an analog input.
    Also make sure the two GNDs of 3.3V and 5V are connected.

    Which sensor and which Zigbee module do you use? Post links to the datasheets.
     
  3. Nayana

    Nayana

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    0
    Jan 20, 2016
  4. Nayana

    Nayana

    5
    0
    Jan 20, 2016
    The configuration at router are:

    atid 5d2
    atdh 0013a200
    atdl 40d6a83f
    atjv1
    atd02
    atir64
    atwr
     
  5. Harald Kapp

    Harald Kapp Moderator Moderator

    9,538
    1,967
    Nov 17, 2011
    ... means you have to connect the analog signal to pin # 20 (D0). The datasheet does not mention a Txx pin which you refer to in your post #1. Make sure your analog signal is connected to the correct pin.
    The analog input signal shall be within the ADC range of 0V...Vddad (+-0.3V max.) As Vddad is connected to Vcc, this means 3.3V. 1.2V should give workeable readings, however at 0...3,3V you'll get better resolution.

    This page shows at least a schematic of the sensor's design. The "analog output" is directly connected to the sensor. Connecting this pin to the ADC input of the Zigbee module may overload the sensor resulting in 0V output. You may have to insert a buffer amplifier (simple non-inverting opamp, use rail-to-rail type!) to decouple the sensor from the ADC.

    As for the AT-commands required to setup the Zigbee module I'm afraid I do not have the time to analyze these for correctness.
     
  6. Nayana

    Nayana

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    0
    Jan 20, 2016
    Thank you :). Will try that out. Thank you once again for your help :)
     
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