Build and Install

** VERY IMPORTANT Raspberry Pi OS Lite (Legacy)** OBAL is tested on Raspberry Pi OS Lite (Legacy), IT DOES NOT WORK ON NEW VERSION BULLSEYE.

Download

Download Binaries from here. Select vehicle type then search for OBAL. For obal copter version 4.2.2

Building The Code

This board does not have any closed source or special drivers. Any Raspberry-Pi board will do the job. All you need is to compile Ardupilot from its main repository. It is straightforward.

git clone https://github.com/ArduPilot/ardupilot.git
cd ardupilot 
git submodule update --init  --recursive
make obal

For Raspberry-Zero you can download its cross-tool from here

you can compile using the following command

./waf configure --toolchain=/opt/cross-pi-gcc/bin/arm-linux-gnueabihf --board obal
./waf rover
./waf copter
./waf plane

IMPORTANT: If you are using OBAL_GY91 you need to apply patch

Deploy Binary

1. Copy ardupilot binary to /home/pi .
2. Create empty file /home/pi/ardupilot.parm using touch /home/pi/ardupilot.parm you can add any initialization parameters to this file. For example for Quadcopter X configuration:

create ardupilot.parm with the following data.

SYSID_THISMAV 1

FRAME_CLASS 1

FRAME_TYPE 1

Run ArduPilot

ArduCopter: sudo /home/pi/arducopter (plus parameter)

ArduPlane: sudo /home/pi/arduplane (plus parameter)

ArduRover: sudo /home/pi/ardurover (plus parameter)

ArduSub: sudo /home/pi/ardusub (plus parameter)

Start Parameter	ArduPilot Serial Port
-A	SERIAL0
-B	SERIAL3
-C	SERIAL1
-D	SERIAL2
-E	SERIAL4
-F	SERIAL5

Check http://ardupilot.org/copter/docs/parameters.html#serial0-baud-serial0-baud-rate to set the right value for SERIALx_BAUD and SERIALx_PROTOCOL

To connect a MAVLink groundstation with IP 192.168.1.123 add -C udp:192.168.1.123:14550

To use MAVLink via radio connected to Serial0 add -C /dev/serial0.

If there is a GPS connected to Serial1 add -B /dev/serial1.

Note: OBAL board default port is serial 0

Example: MAVLink groundstation with IP 192.168.178.26 on port 14550 via wifi and GPS connected to /dev/serial0 and telemetry via OTG /dev/serial1.

sudo /home/pi/arducopter -A udp:192.168.1.123:14550 -B /dev/serial0 -C serial1

Running as a Service

create service file and edit it

sudo nano /lib/systemd/system/ardurover.service

[Unit]
Description=ArduPilot-Rover for Linux OPAL Board
After=systemd-modules-load.service
Documentation=https://docs.obal.com/page.html
Conflicts=arduplane.service arducopter.service ardurover.service

[Service]
Type=single
ExecStart=/home/pi/ardurover -A  udp:**YourTargetIP**:14550:bcast -B /dev/serial0
Restart=on-failure

[Install]
WantedBy=multi-user.target

Above file is for running rover but you can replace ardurover with other binaries e.g. arducopter & arduplane.

Running Service

sudo systemctl enable ardurover.service

sudo systemctl start ardurover.service

CPU Affinity

When running RPI-4 or **RPI-Zero 2W **and using Camera or running other software with ardupilot, it is recommended to give ardupilot 1 or 2 dedicated CPUs to run on. This enhannce Ardupilot schedule timing as we are not running Linux-RT.

The below image shows cpu status using htop when cpu 3 & 4 are isolated using isocpus=2,3

yes values 2 & 3 are mapped to cpu 3 & 4yes values 2 & 3 are mapped to cpu 3 & 4

Steps for using CPU-Affinity Feature is easy.

First free one or more cpus in RPI by adding isolcpus to /boot/cmdline.txt for example below is execution of

cat /boot/cmdline.txt

console=tty1 root=PARTUUID=d9b3f436-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait modules-load=dwc2,g_ether quiet splash plymouth.ignore-serial-consoles isolcpus=2,3

You need to reboot here.

sudo reboot now

in Ardupilot you need to add parameter -c or --cpu-affinity for example:

/home/pi/ardurover -A  udp:**YourTargetIP**:14550:bcast -B /dev/serial0 -c 2,3