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Display Power Problems

A project log for Ye Olde Nowt

Yet another pi zero retro handheld game console.

dehipudeʃhipu 06/23/2017 at 00:054 Comments

As I'm getting more of it to work and testing with Pico8, I'm starting to see that I have a serious problem with the display. As soon as there are white vertical lines on it, it starts making high-pitched noises and do "tv noise" for some frames, and then the whole Raspberry Pi hangs.

Looking at the schematic, I think I made a big mistake connecting the display's power to pi's 3.3V pin. Sure, the display can run both on 3.3V and 5V, and since there is no communication from the display to the pi, there is no problem with voltage incompatibility. I suspect that this display takes a bit too much juice for the pi's regulator.

The solution? I will try to un-solder the VCC pin of the display, and use a wire to connect it to the 5V pins. We will see how that works. One downside is that won't look so good anymore.

If that doesn't help, there is one more possibility -- the display drivers in the kernel may be simply buggy, sending to the display some weird commands that trip it up.

Discussions

moosepr wrote 06/23/2017 at 11:47 point

i would say try experimenting with the speed on the display. on my tft, if i go over 40000000 on the speed, it starts flickering at random intervals

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deʃhipu wrote 06/23/2017 at 11:54 point

No, it was definitely power, rewiring to 5V solved it. Also, those OLED modules can't go over 20MHz on the SPI anyways.

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moosepr wrote 06/23/2017 at 12:32 point

ah, fair play!! one for Rev2 of the PCB :P

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deʃhipu wrote 06/23/2017 at 12:55 point

Well, if there will be version 2, it will probably have that 160x128 OLED secreen you found anyways.

I'm still a bit concerned bout the display making those "chirping" noises. It's probably the coil of the boost converter.

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