Difference between revisions of "Beagleboard:BeagleBone Debian Image Migration"

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(Enabling the ADC)
(U-Boot Overlays (experimental))
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Latest revision as of 11:07, 13 March 2017


What changes were made to sysfs?
3.8 kernel sysfs entry 4.x kernel sysfs entry
/sys/devices/bone_capemgr.* /sys/devices/platform/bone_capemgr
/sys/devices/ocp.* /sys/devices/platform/ocp/
/sys/devices/ocp.*/helper.*/AIN* /sys/bus/iio/devices/iio:device0

Device Tree


Help! My overlay won't load! There's just this weird cape in slot 4.

You've met cape-universal. It is meant to often make overlays unnecessary, but you can also just disable it by changing the following line in /boot/uEnv.txt:

  cmdline=coherent_pool=1M quiet cape_universal=enable


  cmdline=coherent_pool=1M quiet

cape-universal is also automatically disabled if bone_capemgr.enable_partno occurs in the kernel cmdline (even if its argument is blank) or any overlay is already applied via capemgr before cape-universal can be loaded.

Disabling eMMC or HDMI

HDMI and eMMC are now part of the main dtb instead of being virtual CAPEs, which means that to disable these you change the 'dtb' variable in /boot/uEnv.txt instead of using capemgr.disable_partno:

3.8 kernel


4.x kernel


(blank) am335x-boneblack.dtb
BB-BONELT-HDMI,BB-BONELT-HDMIN am335x-boneblack-emmc-overlay.dtb
BB-BONE-EMMC-2G am335x-boneblack-hdmi-overlay.dtb
BB-BONE-EMMC-2G,BB-BONELT-HDMI am335x-boneblack-nhdmi-overlay.dtb
BB-BONE-EMMC-2G,BB-BONELT-HDMI,BB-BONELT-HDMIN am335x-boneblack-overlay.dtb

See also this survey of BeagleBone DTBs.

Enabling the ADC

This requires configuring the ADC via device tree, e.g. by loading the /lib/firmware/BB-ADC-00A0.dtbo overlay (source code) using capemgr:

  echo BB-ADC >/sys/devices/platform/bone_capemgr/slots

The ADC will appear as an IIO device (see /sys/bus/iio/devices/)

Enabling PRUSS

Same story as the ADC except using uio_pruss_enable-00A0.dtbo:

  echo uio_pruss_enable >/sys/devices/platform/bone_capemgr/slots