Raspberry Pi Setup
The Raspberry Pi 4 in the center of the assembly is the literal brain of Lepta and runs all the software. This in turn requires the following operations to be executed on the Raspberry Pi itself.
Setup Leptas backbone
Install Ubuntu Server 20.04 LTS on Raspberry
Download the image ubuntu.com
Install ROS2 Foxy
These instructions follow closely the manuals provided by roboticsbackend.com or on the ROS2 homepage. Refer to these sources in case of trouble.
Setup locale.
sudo locale-gen en_US en_US.UTF-8
sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8
export LANG=en_US.UTF-8
Setup sources.
sudo apt update && sudo apt install curl gnupg2 lsb-release
sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] http://packages.ros.org/ros2/ubuntu $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/ros2.list > /dev/null
Install ROS2.
sudo apt update
sudo apt install ros-foxy-ros-base
To automatically source the ROS files and the Project Leptan files, add these lines to the end of the .bashrc file.
source /opt/ros/foxy/setup.bash
source /home/ubuntu/project-leptan/Software/install/setup.bash
Finally, we need to install Colcon and the CPP compiler.
sudo apt install python3-colcon-common-extensions
sudo apt install g++
Clone the Git repo
git clone --recurse-submodules https://gitlab.com/Combinatrix/project-leptan.git
For the sake of this installation, we will assume, that you clone project leptan into the home directory of the ubuntu installation, i.e. the project directory is /home/ubuntu/project-leptan.
Install Supervisor Requirements
The supervisor is an independent program which observes and indicates the state of Lepta. It monitors the battery voltage and indicates its status on the LED ring, and governs the bluetooth connections. It also starts the hexapod Controller as soon as a joypad is connected.
The supervisor is written in Python 3. Install pip, if not yet present, to install further packages for the supervisor.
sudo apt install python3-pip
WS2812 LEDs
The LED ring uses WS2812 LEDs. Install the neopixel SPI driver for the LED ring.
sudo pip3 install adafruit-circuitpython-neopixel-spi
SPI
SPI is required to drive the LED ring. Detailed instructions can be found at SPI and Neopoixel.
For SPI-bus access create the file /etc/udev/rules.d/50-spi.rules with the following contents.
SUBSYSTEM=="spidev", GROUP="spiuser", MODE="0660"
To make your changes take effect, reboot the Raspberry Pi or reload the udev rules.
Next, copy and paste or type these lines into the terminal as the user you want to give access to the SPI bus.
sudo groupadd spiuser
sudo adduser "$USER" spiuser
INA260
The INA260 is a power meter chip which can measure not only voltage but also current and the according power consumption. Communication is using I2C.
install the git package directly with this command:
pip3 install git+https://github.com/jveitchmichaelis/ina260.git
For I2C-bus access create the file /etc/udev/rules.d/51-i2c.rules with the following contents:
SUBSYSTEM=="i2c-dev", GROUP="i2cuser", MODE="0660"
Again, reboot the Raspberry Pi or reload the udev rules, to make these changes take effect.
Also grant your user access to the I2C bus.
sudo groupadd i2cuser
sudo adduser "$USER" i2cuser
Temperature
The temperature of the raspberry pi chip is used to regulate the speed of the fan for cooling. This is not strictly required, but a raspberry pi 4 runs quite hot without any additional cooling.
pip3 install gpiozero
For GPIO access without root create the file /etc/udev/rules.d/52-gpio.rules with the following contents
SUBSYSTEM=="bcm2835-gpiomem", GROUP="gpio", MODE="0660"
SUBSYSTEM=="gpio", GROUP="gpio", MODE="0660"
SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c '\
chown -R root:gpio /sys/class/gpio && chmod -R 770 /sys/class/gpio;\
chown -R root:gpio /sys/devices/virtual/gpio && chmod -R 770 /sys/devices/virtual/gpio;\
chown -R root:gpio /sys$devpath && chmod -R 770 /sys$devpath\'"
Again, grant access to the GPIO interface to your user.
sudo groupadd gpio
sudo adduser "$USER" gpio
Enable shutdown
sudo chmod u+s /sbin/shutdown
Enable Linux event interface in Python
pip3 install evdev
Setup Joypad
Instruction can be found pimylifeup.com.
Install required Software for XBOX controller.
sudo apt install xboxdrv
This command disables the Enhanced Re-Transmission Mode (ERTM) of the Bluetooth module. With it enabled, the Xbox Controller won’t pair correctly.
echo 'options bluetooth disable_ertm=Y' | sudo tee -a /etc/modprobe.d/bluetooth.conf
Install Bluetooth
sudo apt install pi-bluetooth
Follow a guide like this one in order to pair & connect the controller.
Add the user to the input group in order to access the joypad:
sudo adduser "$USER" input
Further Requirements
sudo apt install ros-foxy-joy
Run the Supervisor
The following command starts the supervisor:
ros2 run supervisor supervisor_node
Start at boot
Only thing left to do is to auto-start the supervisor at boot using Crontab.
Open the crontab file:
crontab -e
Add this line:
@reboot bash -ic "ros2 run supervisor supervisor_node"