Thanks Robert and Jason. For pin 5 and 6, your solution works: Pin 5: $ config-pin P2_35 gpio $ echo in > /sys/class/gpio/gpio86/direction $ cat /sys/bus/iio/devices/iio:device0/in_voltage5_raw 1571
Pin 6: $ config-pin P1_2 gpio $ echo in > /sys/class/gpio/gpio87/direction $ cat /sys/bus/iio/devices/iio:device0/in_voltage6_raw 1571 Because of the voltage divider, the values are half of the "normal" values. But I still can't get pin 7 to work: $ while [ 1 ]; do cat /sys/bus/iio/devices/iio:device0/in_voltage7_raw; done This gives me a sequence of values starting around 1600 dropping by about 10 every second, unrelated to my input, slowing down to about 658. Sort of like the voltage if you were discharging a capacitor. So analog input 7 seems to be measuring something, but I don't know what. Maybe some PMIC thing? (I'm using Linux beaglebone 4.4.91-ti-r133 #1 SMP Tue Oct 10 05:18:08 UTC 2017 armv7l GNU/Linux) Ken On Tuesday, December 5, 2017 at 10:03:06 AM UTC-8, Jason Kridner wrote: > > > > On Tue, Dec 5, 2017 at 10:00 AM Robert Nelson <robert...@gmail.com > <javascript:>> wrote: > >> On Sun, Dec 3, 2017 at 1:07 PM, Ken Shirriff <ken.sh...@gmail.com >> <javascript:>> 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 beagleboard...@googlegroups.com <javascript:>. >> 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 beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/8a366e68-aa6f-4847-9a14-d2abb782d351%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
