On Thursday, March 13, 2014 8:48:40 AM UTC-6, cagri yilmaz wrote: > > I used for AIN1 (P9-40) connected a PTC with parallel 480 ohm resistor and > P9-03 3.3V and P9_34 AGND. I did not used VADC P9-32 as reference. Is there > anybody knows what I did wrong? >
Oh oh... The absolute maximum allowed input on ANIx is 2.1 V per the AM335x datasheet. You may have damaged your CPU by connecting to 3.3V. The PTC should be used to form a resistor divider between VADC (P9-32) and GND_ADC (P9-34). The voltage out of the divider will change as the value of the PTC resistor changes. See the crude schematic below. VADC \ Fixed Resistor / AIN1 \ PTC / GND_ADC AINx will always be less than VADC and greater than GND_ADC. HTH Dennis Cote -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.