Sharp GP2D12 IR Distance Sensors Noise

Discussion in 'The Projects Forum' started by Dalaran, Dec 26, 2009.

  1. Dalaran

    Thread Starter Active Member

    Dec 3, 2009
    I am using 2 of these sensors to judge the difference in distance on the two sides. These are then to be read by the ADC of a PIC and compared internally.

    As a first practice with this sensor I hooked it up 5V and GND and had the analogue out pin connected directly to a scope. Originally I was seeing large (500mV) spikes multiple times a second. I placed a resistor (1k) and cap (100nF) from the analogue out pin to ground which seemed to clear it up quite well. However I am seeing close to 50mV of random noise no matter what I do. I didn't see anything in the datasheet but is this expected from these sensors? I was under the impression they would be a little more accurate than 50mV, but I could be wrong.

    Anyone used these with similar experiences?

  2. bertus


    Apr 5, 2008

    Do you have decoupling capacitors on the powerlines of the chips?
    These capacitors will suppress pulses going from one chip to the other.
    Take 100 nf on the power lines of each chip.

  3. BMorse

    Senior Member

    Sep 26, 2009
    The minimum typical voltage on the output at any time for these sensors is around .4V

    The Voltage output with object at 80cm is .55 Volts, at 10cm it should be around 2.25 Volts.