From: maxmike <[email protected]> Reply-To: "[email protected]" <[email protected]> Date: Monday, January 19, 2015 at 5:10 PM To: "[email protected]" <[email protected]> Subject: [beagleboard] Same wire going to adc and comparator kills interrupts
> I have the output of an op amp go directly to the BBB adc and the values are > read correctly. > But, the same wire is going to a comparator to generate interrupts. > It looks like the comparator is not firing all the way to ground because of > the adc drag. > I thought of placing a 1K resistor from the adc input to ground but that does > nothing. > Anything higher is going to bother the adc. I'm stumped. Well, it depends on the opamp. Some opamps are not able to drive all the way to 0V, but as long as it goes below the logic low for your I/O input, it shouldn¹t matter. If you really want an opamp that goes to zero, choose one that is capable to operating rail to rail. Also, the opamp feedback circuit is important because you are going to want some hysteresis or your GPIO input might see some noise close to the trigger point. Regards, John > > > -- > 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 [email protected]. > For more options, visit https://groups.google.com/d/optout. -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
