2.5 TFT display compatability with Pi 4B and Composite cable

Support Product Questions
1

Hi there,

I’m hoping to set up a simple video loop using:

ADA912 - NTSC / PAL TFT Display - 2.5
ADA2881 - AV and RCA Composite Cable for Raspberry Pi
Raspberry Pi 4B

Can you tell me if all of these bits are compatible with one another?

Thanks.

Sabrina

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2

Hi Sabrina,

The Raspberry Pi 4B can output in composite video format via the 3.5mm jack and the AV and RCA Composite Cable that you’ve referenced but the composite video does have some limitations.

Composite video requires certain timings which means the Pi4Bs processor must be slowed down slightly for the composite video to work. So that every Pi4 doesn’t run slower for no reason composite video is disabled by default and needs to be enabled either by changing a line in the config.text file on the SD card, or the graphical configuration editor.

A Raspberry Pi engineer goes through the changes to make and explain the limitations better in this thread.
https://forums.raspberrypi.com/viewtopic.php?t=251277

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3

Thanks for your help Trent.

I’ve read the link and it’s not clear to me if the composite slowing the Pi down means the video playback will be slowed down…?

I want to make a basic video looper with the adafruit looper, so it looks like it might make more sense to go with an earlier model of the Pi if that will avoid this problem.

I’m new to this and successfully managed to set up the looper with a 4B (with a standard full HD screen with HDMI output/input…) and just wanted to be able to replicate but I guess it was never going to be that easy using non-standard displays!

Thanks again,

Sabrina

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4

Hi Sabrina,

Composite video requires the Pi to run slower than if it was just using HDMI, but the speed difference isn’t likely to be enough to cause an issue with your video looper. Even after being slowed down on a Pi 4B it will still be faster than using a Pi3B+, so there’s no advantage to using a previous generation Pi just for composite video.

It’d be worth looking into some other small form factor displays though.
There is a 2.8-inch display that sits directly on the Pis GPIO header and would require less setup, while also being a touch screen.
Alternatively, we have a 3.5-inch display that also has a touchscreen and the option of a GPIO or HDMI connector.

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5

Thanks for your advice Trent - I’ve gone with 2 of the 2.5 and one of the 3.5. Will see how I go!

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