Interface LDR with micro controller without using a ADC.

Discussion in 'Embedded Systems and Microcontrollers' started by thar07, Feb 11, 2015.

  1. thar07

    Thread Starter Member

    Jan 3, 2015
    71
    0
    Can LDR interface with a micro-controller without using a ACD ?
    TO use as a on/off switch which gives 0V and 5V s.
     
  2. Magician

    New Member

    Aug 18, 2014
    13
    6
    Sure, you don't have to use ADC. Connect LDR with a resistor in series between power line and ground. Middle point goes to input of the uCPU. The problem is LDR has wide dynamic range, over 10^6, it's resistance change from ~100 Ohm in bright lighting condition to ~100 M Ohm in darkness. It's may be tricky to select right loading resistor
     
    thar07 likes this.
  3. BobTPH

    Active Member

    Jun 5, 2013
    782
    114
    Use a Schmitt trigger input if it is available on your micro controller.

    Bob
     
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