Control Pad

Breaks out monitor controls into a desktop based keypad. Also runs a simple webserver on port 1602 to display text on the screen from api requests.

Hardware

Parts List

• 3D Printed Enclosure
• Raspberry Pi Zero W
• 16x2 HD44780 LCD Display
• 4x4 Matrix Keypad
• 10K Trimpot
• Female/Female Jumper Wires
• Micro USB Cable for power
• Mini HDMI Cable
• 4x M3x12 bolts
• 4x 10mm self adhesive rubber feet

Assembly

See Adafruit's guides to wiring the display and keypad.
The pins on the lcd and display must be bent ~45° in order for them to fit inside the case.
The protrusions in the 3d model sized for a ~18mm cylinder are to hold a chunk of steel to give it some extra weight.

Software

Prerequisites

Controlling the monitor relies on the DDC/CI protocol. This is done over the /dev/i2c-2 interface which is disabled by default. See ddcutil's documentation for details. Enabling this requires adding a line to config.txt and a reboot.

echo "dtparam=i2c2_iknowwhatimdoing" | sudo tee -a /boot/firmware/config.txt
sudo reboot now

From a fresh Pi OS Lite image, ddcutil, pip and git are required.

sudo apt install ddcutil python3-pip git -y

Installation

git clone https://github.com/ChunkLightTuna/monitor_control.git
cd monitor_control
python -m venv .venv
. .venv/bin/activate
pip install -r requirements.txt

Config

Pin mappings are defined in pinout.json. Note these are by GPIO/BCM number, not their physical position. If you wire your pi up differently adjust the json accordingly.

Monitor IDs to be used under displays can be retrieved using the following ddcutil command:

ddcutil capabilities |  awk  '/Feature: 60/{f=1; next} f&&!/Feature/{print} /Feature/{f=0}'

Displaying weather forecast requires the OPEN_WEATHER_API_KEY, LAT and LONG environment variables be set. These may be defined in monitor_control.service. Port number may be modified from the service file as well.

Running

uvicorn main:app --host 0.0.0.0 will run the app. From the initial screen press 2 or 8 to go to the Monitor Control menu.
Pressing A, entering a number, and then # will set your display's audio level.
B will do the same for brightness. C will select the previous display, and D the next.

To persist as a systemd service, run the following:

sed -e "s/\${DIR}/$(pwd | sed 's|/|\\\/|g')\/src/g" monitor_control.sample.service > monitor_control.service
systemctl enable --now "$(pwd)/monitor_control.service"