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So I have a few cheap 3.5 tfts that you can find online for around $15. I use the instructions here to get it working for retropie:

https://www.hackster.io/manuelfelipe_ramos/how-to-install-kuman-tft-3-5-for-raspberry-pi-and-retropie-c49800

Now the performance on my raspberry pi 3b with this LCD panel is fairly good. Not as good as adafruits, but unbeatable for the money. The issue is when I install it on my raspberry pi zero w. The frame rates are terrible and practically unplayable on gba games. Oddly enough there is no lag or issue at all when I use the HDMI output on the zero.

I'm wondering if maybe there are some settings I can adjust, or, why is there better peformance on the pi 3b? I'm completely aware of the hardware differences. I mean specifically? Is it the CPU? RAM? power? GPIO?

Is there anything I can do to hack around this?

Thanks for all and any insight. I'm just learning on the Pi and wasn't able to find any answers to this specific issue (zero w + cheap 3.5 tft + retropie).

  • 3
    Have you compared the specs? – joan Nov 21 '17 at 21:44
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The Pi 3 has a 1.2GHz quad-core processor and 1GB of RAM, while the Pi Zero has a 1GHz single-core processor and 512MB of RAM. It's expected that the Pi 3 would be faster on things like this. There's not really anything you can do.

Your comment about the HDMI output not having this trouble does make some sense. I don't think that the BCM2837 (the chip in the Pi 3) has a different GPU from the BCM2835 (in the Pi Zero), so the speed would be roughly the same for both on HDMI.

But with the touchscreen, speed is throttled by the GPIO pins, which (to my knowledge) are controlled by the CPU, which is slower for the Zero.

Hope this helps.

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