BBB Audio Cape RevB Getting Started

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This guide is intended to walk through the basic instructions on how to get your Audio Cape working. The instructions below are performed with following kernel and may vary for different kernel versions.

   root@beaglebone:~# uname -a
   Linux beaglebone 3.8.13-bone47 #1 SMP Fri Apr 11 01:36:09 UTC 2014 armv7l GNU/Linux

Load the device tree file=

Ensure your BBB is connected to the internet. Download the provided device tree files and decompress it. You may end up doing something like this:

   root@beaglebone:~# wget http://elinux.org/images/1/10/BB-BONE-AUDI-02-00A0.zip
   root@beaglebone:~# unzip BB-BONE-AUDI-02-00A0.zip

Compile the device tree file and move it to /lib/firmware:

   root@beaglebone:~# dtc -O dtb -o BB-BONE-AUDI-02-00A0.dtbo -b 0 -@ BB-BONE-AUDI-02-00A0.dts
   root@beaglebone:~# mv BB-BONE-AUDI-02-00A0.dtbo /lib/firmware

Since this Audio Cape uses the same audio signal from the onboard HDMI interface, you need to disable the audio portion of the HDMI by edit the uEnv.txt at /boot/uboot. Add this line to the uEnv.txt file.

   optargs=capemgr.disable_partno=BB-BONELT-HDMI capemgr.enable_partno=BB-BONE-AUDI-02

Reboot your BBB. Log in and check the capemgr

   root@beaglebone:~# cat /sys/devices/bone_capemgr*/slots
       0: 54:PF--- 
       1: 55:PF--- 
       2: 56:PF--- 
       3: 57:PF--- 
       4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
       5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
       6: ff:P-O-L Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN

Note that the "virtual cape" BB-BONELT-HDMIN is loaded instead of the BB-BONELT-HDMI. The difference between the two "capes" is that the BB-BONELT-HDMIN does not include the audio protion. By doing this, we can now load the Audio Cape device tree:

   root@beaglebone:~# echo BB-BONE-AUDI-02 > /sys/devices/bone_capemgr*/slots
   root@beaglebone:~# cat /sys/devices/bone_capemgr*/slots
       0: 54:PF--- 
       1: 55:PF--- 
       2: 56:PF--- 
       3: 57:PF--- 
       4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
       5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
       6: ff:P-O-L Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN
       7: ff:P-O-L Override Board Name,00A0,Override Manuf,BB-BONE-AUDI-02

The Audio Cape is now loaded.