> > *I need to maintain the ratio of the two voltages and I don't know how > high they will get. Milliseconds is OK, but faster is better. I didn't > realize the PRU's could do ADC.* >
Technically, they can't. But they can access the on chip ADC, and very fast. It's the most deterministic was to access the on chip ADC. Unless, perhaps you ran the board bare metal. Which does not make much sense . . . On Fri, Oct 30, 2015 at 10:16 AM, John <ra...@mediacombb.net> wrote: > > I need to maintain the ratio of the two voltages and I don't know how high > they will get. Milliseconds is OK, but faster is better. I didn't realize > the PRU's could do ADC. > > > At 11:00 AM 10/30/2015, Przemek Klosowski wrote: > >> You can't feed more than 1.8V to ADC without damaging it. You can, >> however, scale it with a simple resistor divider (resistor R1 connected >> between the ground and second resistor R2, which is then connected to >> your signal), and hook the ADC to the middle of the divider where it will >> be scaled down by the ratio R1/(R1+R2). How quickly do you want the result? >> If it's miliseconds, Linux is perfectly capable of that; if microseconds, >> then PRUs can do it; otherwise, you'd have to come with an analog >> multiplier circuit. >> >> On Fri, Oct 30, 2015 at 7:23 AM, John <<mailto:ra...@mediacombb.net> >> ra...@mediacombb.net> wrote: >> >> I'm a hobbyist with a recent BBB and I want to use a couple of ADC >> channels in real time (alternate). As nearly as I can tell, this is not >> supported by the two risk units. >> Have I missed something? >> >> BBB and Linux are new to me. One of the things I would like to do is >> compute a ratio between two voltages, each of which might exceed 1.8 VDC. >> One solution might be to use DACs to sent feedback voltages to operational >> amplifiers that are supplied by 1.8 VDC. The goal is to determine the >> ratio as quickly as possible and without waiting for Linux to get around to >> it (waiting for the ADC to happen). >> >> 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 beagleboard+unsubscr...@googlegroups.com. > 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 beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
