4 Displays with diffrent output using Raspberry Pis

Question

Core Problem: I need 4 displays to show diffrent output (simple images)

For this kind of "Video Wall" problem, most solutions recommend one RPi for each display/monitor in a master/slave configuration. My goal is to be cost efficient, so i want to reuse laptop displays and stuff i already have. The GUI will be programmed in python using tkinter oder kivy. Data for the output images should be acquired via a wireless network connection.

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needed Features:

1. Network connection
2. energy saving (battery, powerbank)
3. different output for each display
4. HDMI/VGA output connection (for LCD-Controller Boards needed for the FPD-Link (LVDS) Laptop Displays)
5. not oversized (i dont want to use a RPi4 if a RPi Zero is enough ;))

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what i already have:

• RPi 4
• RPi 3 B+
• 2x RPi Zeros
• 4 VGA LCD-Controllerboards (MT6820-b v2.0)
• 1 HDMI+VGA TTL+LVDS Controller Board
• 4 LVDS-Displays

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Question: What is the easiest and cheapest configuration solving my core problem as stated above? Do you have any suggestions of possible subsystems i need to control the output images on the individual display?

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possible solutions:

1. one RPi 4 with its two HDMI outputs and maybe one VGA output using an adapter board for the GPIO-Pins. The forth output could be a RPi Zero as slave.
2. little bit better option, as i need the RPi4 for another project: RPi 3B+ with its HDMI output plus the GPIO VGA adapter board and two RPi Zeros as slaves
3. maybe its even possible to just use 4 RPi Zeros, but the missing network connection introduces more problems.

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Thank you for your help!

Answer 1

The easiest would be to use 1 RPi for every screen to ensure scalability, and wired network connections between the nodes to avoid delays and dropouts. Configurations with multiple displays per node will be substantially more tricky to set up and operate.

I think the cheapest configuration would be 4 x RPi Zero ($5 a piece) with USB network adapters (less than $5 a piece) and small SD cards ($5-$10 a piece) each driving one screen. You will also need 4 x LVDS controller boards supporting HDMI ($15 a piece), so that you can use your existing LVDS displays, and a 5-port network switch (another $15) plus some power supplies and cables. A total of about $200.