TABLE OF CONTENTS
DAKboard OS devices, whether purchased from our Shop, one of our Resellers, or done as a DIY project all use HDMI as their method to connect to the display. This article intends to cover the various HDMI connections you will find on Orange Pi and Raspberry Pi computers we use and you can buy and how they play an integral part of your complete Display package.
DAKboard OS and HDMI:
The DAKboard OS not only uses the capabilities of HDMI to send and receive Audio and Video, but it also uses these lines of communication to gather information on your Monitor/TV's make and model. Furthermore, we utilize the CEC capabilities of most modern TVs and Monitors to allow you to turn on and off your Monitor/TV using the DAKBoard device's built-in On/Off (Sleep) Schedule.
Because we use advanced features such as CEC, when a DAKboard OS device first boots up, it reaches out to the connected Monitor/TV to confirm it is using the HDMI connection and waits for a response. Sometimes it fails to get this response and reacts by rebooting itself to try and establish communication. If your DAKboard OS device is boot looping, only going to the DAKboard loading page, or a rainbow-colored screen repeatedly, this means that your DAKboard is not getting the response from your Monitor/TV.
This can be a sign that either your HDMI Cable is bad or your connection to the CPU and Monitor/TV is loose. If the cable is bad it will need to be replaced if the connection is loose, you can correct this by simply unplugging the power to your DAKboard CPU, unplugging both the HDMI connection on the CPU and the Monitor/TV, then plugging the HDMI cable back in making sure the connection is sound on both ends. Then simply plug the power back in and your device will start up.
HDMI connections of the CPUs v3 and v4:
In our current models, the v3 is powered by the Orange Pi 3 LTS, and the v4 is powered by the Raspberry Pi 4B. As seen below, the v3 has a single standard HDMI output:
While the v4 supports Dual Micro HDMI outputs.
Though the v4 has two HDMIs out, they do not function independently. This means that the Secondary HDMI output, the one furthest from the power supply, is just a mirrored copy of the Primary HDMI output. You can use this if you want to hook up two monitors to show the same output.
Below is a matrix of what is supported by these HDMI Outputs:
| Device | Supported Output | Video | Audio | CEC | Individual Screen | Resolutions |
| CPU v3 | HDMI | Yes | Yes | Yes | Yes | 2k UW, 4k, 1080p, 720p |
| CPU v4 | Primary Micro HDMI | Yes | Yes | Yes | Yes | 2k & HD UW, 4k, 1080p, 720p |
| CPU v4 | Secondary Micro HDMI | Yes | No | Yes | No | 2k & HD UW, 4k, 1080p, 720p |
NOTE: As of version 4.01 and above, the DAKboard CPU v4 will support audio through both the Primary and Secondary HDMI outputs as well as through the auxiliary headphone output. If you are running an older version, 3.54 and below, you will need to upgrade to get these added features. You can upgrade to the latest version of the OS by following the steps in our article Raspberry Pi - Download and Install the DAKboard OS.
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