On Tue, Dec 5, 2017 at 10:00 AM Robert Nelson <[email protected]> wrote:
> On Sun, Dec 3, 2017 at 1:07 PM, Ken Shirriff <[email protected]> > wrote: > > I can read analog inputs 0-4 from > > /sys/bus/iio/devices/iio:device0/in_voltageN_raw but I can't get analog > > inputs 5-7 to work. Inputs 5 and 6 don't have analog as a choice in > > config-pin: > > > > $ config-pin -l P1_2 > > default gpio gpio_pu gpio_pd pruout pruin > > > > Analog input 7 (P2_36) doesn't have any other function, but it ignores > any > > analog input voltage. > > > > Is there a trick to using inputs 5-7 or is support under development? > > Since 5-7 ADC's are shared with a normal pin, you need to stick the > gpio in gpio mode with config-pin.. (no pull-up, no pull-down) then it > might work.. > > Haven't personally tried this yet.. > I tested all 3 inputs as part of the board bring-up/validation process, but I was using a different device tree. I'm trying to get back to it with what Robert ships in the latest images, hopefully in the next day or so, but I'd like to provide some notes that might be of some use: For 5 and 6, yeah, Robert's right on making sure the GPIO is set to input mode (should be default?) and that there is no pull-up/pull-down enabled on the pin. Do note, however, that there is a 10k pull-down due to the resistor divider on the input. All voltages on the ADC will be half of what they are on the headerpin. For 7, there is an analog mux, but it should default to the status of the pin. There are some voltages internal to the PMIC that could be read, put the header pin status should be the default. > > Regards, > > -- > Robert Nelson > https://rcn-ee.com/ > > -- > 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]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/CAOCHtYjKoCF5-ZULWhZUdefCMZo84H1g_1tmPQjaUFOO4v8Xpg%40mail.gmail.com > . > For more options, visit https://groups.google.com/d/optout. > -- https://beagleboard.org/about -- 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CA%2BT6QP%3DBLZtnHiRnGfTT9Fvf0tG-x9-%3DgKYBffvxFYK3u-1R1Q%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
