interfacing pt100 to pic

Discussion in 'Embedded Systems and Microcontrollers' started by scientistumair, Jan 3, 2010.

  1. scientistumair

    scientistumair Thread Starter New Member

    Oct 23, 2009
    I want to display and control(on/off control) temperature using pt100 as sensor and pic16f877A. I built 1mA current source using lm324 quad operational amplifier(two opam used for current source) then voltage folower then noninverting amplifier my voltage range after amplification is 2.5 to 5V.But when I give this voltage to pic16f877A to channel 0 then the voltage drop to -0.785V constant at input pin of pic16 even the resistance of pt100 and corresponding voltage changes and pic cannot control temperature(continous on signal at putput).