On Fri, Oct 13, 2017 at 8:13 AM, <[email protected]> wrote: > > We just purchased a group of BeagleBone Black Rev. C boards. We’re trying > to get the ADC working properly. We use a Adafruit BeagleBone Proto cape. > We have a pressure sensor connected to pin P9_39 (AIN0). The pressure > sensor produces millivoltage readings. We only sample the reading hourly in > production so we’re not using continuous buffered input. This setup worked > accurately with the previous BBB Rec C boards using Debian 7. I can’t seem > to get an accurate reading under Debian 8 though. I assume I’m not > configuring the AIN overlay correctly. I get readings but they are not > correct. The values are more than double what I’m reading by using a > digital multimeter on P9_39 (202mv digital multimeter 464mv AIN0). If I > move the cape from the new Debian 8 BBB Rev C to an earlier Debian 7 BBB Rev > C the readings are correct: same cape, same sensor, same power supply. > > > I've tried 3 new BBB Rev C and get the same result
You can install 3.8.13 in Debian 8.. The easiest way is just: cd /opt/scripts/tools/ sudo ./update_kernel.sh --bone-channel --stable sudo reboot and you'll have 3.8.13-boneX installed.. https://elinux.org/BeagleBoardDebian#Install_Latest_Kernel_Image > > > > I’ve tried both these two tutorials to build ADC into the overlay. Both > tutorial produce working overlays with identical, incorrect readings on > AIN0. > > > https://www.teachmemicro.com/beaglebone-black-adc/ <- specific to Ubuntu 16 > but I gave it a whirl > > > > https://gist.github.com/matthewmcneely/bf44655c74096ff96475 > > > I tried loading a number of distribution provided dtb's, disabling HDMI and > Audio. In addition, I downloaded Robert Nelsons dtb-rebuilder and compiled > new dtbo's using the stanza's suggested in the tutorials above : > https://github.com/RobertCNelson/dtb-rebuilder > > > > I’ve tried building overlays using the stock out of the box kernel and after > running apt dist-upgrade. In each case I can see the overlay loaded but the > values I read are always the same and incorrect. > > > /boot/uEnv.txt > > #dtb=am335x-boneblack.dtb > dtb=am335x-boneblack-overlay.dtb > cape_disable=bone_capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN > #cape_enable=bone_capemgr.enable_partno= > cmdline=coherent_pool=1M quiet cape_universal=enable > > cat /sys/devices/platform/bone_capemgr/slots > > 0: PF---- -1 > > 1: PF---- -1 > > 2: PF---- -1 > > 3: PF---- -1 > > 4: P-O-L- 0 Override Board Name,00A0,Override Manuf,univ-emmc > > 5: P-O-L- 1 Override Board Name,00A0,Override Manuf,BB-ADC > > > > uname -a : Linux beaglebone 4.1.15-ti-rt-r43 #1 SMP PREEMPT RT Thu Jan 21 > 20:13:58 UTC 2016 armv7l GNU/Linux Yuck "4.1.x"... 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/CAOCHtYi-DgTeSgjA0vmuMFnWR7%3DmAoYuVwauMuCh9%3DnMdAtpYg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
