You could connect the sensor (without a separate pull-up) to an input=20 with internal pull-up that is a Schmidt input. Enable internal pull-up,=20 read the input, then disable internal pull-up. Kerry alan smith wrote: > No, just to detect if the circuit is open > > --- On Mon, 2/28/11, Mark Rages wrote: > > =20 >> From: Mark Rages >> Subject: Re: [PIC] open circuit detection >> To: "Microcontroller discussion list - Public." >> Date: Monday, February 28, 2011, 2:15 PM >> On Mon, Feb 28, 2011 at 3:07 PM, alan >> smith >> wrote: >> =20 >>> I have a sensor, that when its activated, it goes from >>> =20 >> a 15ohm to open circuit. This is a battery powered device, >> so low current is critical. It will bounce back and forth, >> as its a motion detector of sorts. >> =20 >>> The approach I was going to take (and build up to test >>> =20 >> later) is to put a 330K resistor in series being fed by the >> box 3.3V power, and connect the A/D of the PIC between the >> sensor and the resistor. Normally it will pull some small >> amount of current and thus a voltage drop to measure, and on >> a open circuit if course it should read zero. >> =20 >>> Any other ideas on measuring for an open circuit with >>> =20 >> very low power consumption? >> =20 >> Are you trying to measure on/off or a range of values? >> >> Regards, >> Mark >> markrages@gmail >> >> --=20 >> Mark Rages, Engineer >> Midwest Telecine LLC >> markrages@midwesttelecine.com >> >> --=20 >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> =20 > > > =20 > > =20 --=20 Internal Virus Database is out-of-date. Checked by AVG Anti-Virus. Version: 7.0.289 / Virus Database: 267.11.13 - Release Date: 10/6/05 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .