Source Compiling Bela

On the BeagleBone:

Pre-requisites:

Install Xenomai
Preferrably install the Cape Compatibility Layer if your kernel allows.
Clone the repo git clone https://github.com/giuliomoro/Bela-dhruva.git and then make sure that you are root user and then clone the Bela repo in /root/.

Install am335x PRU package: Become super user by typing sudo -i and then git clone https://github.com/beagleboard/am335x_pru_package and then cd into the cloned directory and then
run
```
make && make install
```

Download and install seasocks libraries:
Also make sure that you have latest version of cmake installed on your BBB.

git clone https://github.com/mattgodbolt/seasocks
cd seasocks/
ls
mkdir build
cd build/
cmake .. -DDEFLATE_SUPPORT=OFF -DUNITTESTS=OFF
make
make install
  

Install libne10

sudo apt update
sudo apt install libne10-dev
  

Install alsa and some libasound2:

sudo apt-get install alsa-utils libasound2-dev

While you're still su:

dpkg -i /root/Bela/resources/stretch/deb/libpd-xenomai-3-dev_0.11.0-Bela-1_armhf.deb
  

Finally, go to the Bela directory and run

make lib

and that shall build your core Bela Code. Now to test if things went fine you will have to make a folder projects inside the /root/Bela inside which you can copy any example that you like and then run

sudo make PROJECT=sinetone run CL=-v
  

In this case I am building the sinetone example. The ideal output(with the BELA Cape on the BBB) would be that you hear a shrill sine tone from the output speakers(which are externally connected to the BELA cape) and the following console output:

Failed to stop bela_startup.service: Unit bela_startup.service not loaded.
No process to kill
Running /root/Bela/projects/sample-streamer/sample-streamer -v
Xenomai not explicitly inited
Xenomai is going to be inited by us
Bela_initAudio()
Starting with period size 16 ;analog enabled
DAC level 0.000000 dB; ADC level 0.000000 dB; headphone level -6.000000 dB
Detected hardware: Bela
Hardware specified by user:
Hardware specified in belaconfig:
Hardware to be used: Bela
Bela_getHwConfigPrivate()
fifoFactor: 1
core audioFrames: 16
Project name: sample-streamer
PRU memory mapped to ARM:
digital: 0xb60ad000 0xb60ad400
audio: 0xb60ae000 0xb60ae040 0xb60ae080 0xb60ae0c0
analog: 0xb609e000 0xb609e080 0xb609e100 0xb609e180
analog offset: 0xffff2000 0xffff2080 0xffff2100 0xffff2180
Bela_startAudio
startAudioInilne
Using embedded PRU code
_________________Audio Thread!
  

Contingencies

ERROR 127:

root@beaglebone:~/Bela# sudo make PROJECT=exampleTempProject run CL=-v
Failed to stop bela_startup.service: Unit bela_startup.service not loaded.
No process to kill
Running /root/Bela/projects/exampleTempProject/exampleTempProject -v
/root/Bela/projects/exampleTempProject/exampleTempProject: error while loading shared libraries: libcobalt.so.2: cannot open shared object file: No such file or directory
make: *** [Makefile:588: runonly] Error 127
  

Then run this

ldconfig /usr/xenomai/lib/

Sinetone example runs but without audio output
Make sure that you disable/comment out all other overlays in the /boot/uEnv.txt file and only have this one under Additional custom capes enabled:
```
###Additional custom capes
uboot_overlay_addr4=/lib/firmware/BB-BELA-00A1.dtbo
```

Note: BBAI users have to lead the custom overlay that I have written called the BBAI-BELA-00A1.dts which uses the CCL. So make sure you have installed the Cape Compat. Layer properly as well.

If you get the following error:

root@beaglebone:~/Bela# sudo make PROJECT=exampleTempProject run CL=-v
Failed to stop bela_startup.service: Unit bela_startup.service not loaded.
No process to kill
Running /root/Bela/projects/exampleTempProject/exampleTempProject -v
Xenomai not explicitly inited
Xenomai is going to be inited by us
Bela_initAudio()
Starting with period size 16 ;analog enabled
DAC level 0.000000 dB; ADC level 0.000000 dB; headphone level -6.000000 dB
Detected hardware: Bela
Hardware specified by user:
Hardware specified in belaconfig:
Hardware to be used: Bela
Bela_getHwConfigPrivate()
fifoFactor: 1
core audioFrames: 16
Project name: exampleTempProject
PRU memory mapped to ARM:
digital: 0xb620f000 0xb620f400
audio: 0xb6210000 0xb6210040 0xb6210080 0xb62100c0
analog: 0xb6200000 0xb6200080 0xb6200100 0xb6200180
analog offset: 0xffff2000 0xffff2080 0xffff2100 0xffff2180
Bela_startAudio
startAudioInilne
Failed to open the kernel driver: (2) No such file or directory.
Maybe try
  modprobe rtdm_pruss_irq
?
Error: unable to start PRU from
Error: unable to start real-time audio
Stopping audio...
Failed to join audio thread: (3) No such process
Bela_cleanupAudio()
make: *** [Makefile:588: runonly] Error 1
Trying modprobe rtdm_pruss_irq returns
modprobe: FATAL: Module rtdm_pruss_irq not found in directory /lib/modules/4.14.108-ti-xenomai-r143

then build with BELA_USE_DEFINE=BELA_USE_POLL for now. This will remove the dependency on the rtdm_pruss_irq driver. (As of 20 Aug, 2021 this step is very much still required as the interrupts part could not be accomplished yet on the AM57xx.

Resources

BB.org overlays