Raspberry Pi

HDMI Doesn't Output Video When Plugging in Display After Boot
ISSUE:  Raspberry Pi does not display video output when connecting HDMI monitor after startup. Keyboard and mouse input do not wake up display and rebooting outputs video. Raspberry Pi is responsive to ping/ssh and other services. 

 RESOLUTION:  This functionality is disabled by default. To enable, edit /boot/config.txt and add/uncomment the line  hdmi_force_hotplug=1 . This file also contains  disable_overscan=1  which will fix issues with black borders if not set up during initial configuration. Once changes to the file are made, a reboot is needed to apply. 

 As the file requires root permissions, can be edited with  sudo nano /boot/config.txt .

Install UniFi Controller on Raspberry Pi
Install and update 64-bit OS. 

 Set a static IP. From the terminal enter  nano /etc/dhcpcd.conf  and uncomment the lines under Example static IP configuration. Reboot to apply and test. 

 Install rng-tools with  sudo apt install rng-tools . The config in /etc/default/rng-tools-debian should be modified. Uncomment the line with HRNGDEVICE=/dev/hrng . Once the file is saved restart with  sudo systemctl restart rng-tools . 

 Prior to installing the UniFi controller, an older version of libssl needs to be installed and mongodb installed, enabled, and started.

 wget http://ports.ubuntu.com/pool/main/o/openssl/libssl1.0.0_1.0.2g-1ubuntu4_arm64.deb -O libssl1.0.deb

sudo dpkg -i libssl1.0.deb

wget https://repo.mongodb.org/apt/ubuntu/dists/xenial/mongodb-org/3.6/multiverse/binary-arm64/mongodb-org-server_3.6.22_arm64.deb -O mongodb.deb

sudo dpkg -i mongodb.deb

sudo systemctl enable mongod

sudo systemctl start mongod 

 

 Rather than downloading and installing the Debian package, we will add the repository so that it can be managed with apt. Enter echo 'deb [arch=amd64 signed-by=/usr/share/keyrings/ubiquiti-archive-keyring.gpg] https://www.ui.com/downloads/unifi/debian stable ubiquiti' | sudo tee /etc/apt/sources.list.d/100-ubnt-unifi.list >/dev/null to add the repository to the apt configuration. Next, add the key to your trusted keys with curl https://dl.ui.com/unifi/unifi-repo.gpg | sudo tee /usr/share/keyrings/ubiquiti-archive-keyring.gpg >/dev/null . 

 Run  sudo apt update  to update the package repository. 

 Install the UniFi package with  sudo apt install unifi . Answer yes to continue. 

 Check the service status with  sudo service unifi status . If it hasn't started install Java with sudo apt install openjdk-17-jre-headless unifi . 

 Run  sudo service unifi start  to start the service again. 

 You should now be able to access the controller at  https://{your-ip}:8443 and begin configuration.