On Tue, Dec 5, 2017 at 2:21 PM Ken Shirriff <[email protected]> wrote:
> 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 not sure how to check the status of the analog mux. Someone posted a driver patch on the TI e2e forum to change the status. Maybe we should carry that patch or help submit to mainline? https://e2e.ti.com/support/arm/sitara_arm/f/791/t/256567 Out of curiosity, can you try: sudo i2cset -y -f 0 0x24 9 5 sudo i2cget -y -f 0 0x24 9 sudo cat /sys/bus/iio/devices/iio:device0/in_voltage7_raw I pulled the magic numbers from the patch and the files it references. > > (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 <[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/8a366e68-aa6f-4847-9a14-d2abb782d351%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/8a366e68-aa6f-4847-9a14-d2abb782d351%40googlegroups.com?utm_medium=email&utm_source=footer> > . > 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%2BT6QPkYrrtzEeVM7dXeTnWh3Qp2uTfvZoVDWnfa%2BHi2mVXhdg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
