I was reviewing my TFT setup, and I came across this example of how to wire things up.
I am curious, but are the 1k resistors really needed for the screen
shown in the example? It's the only one I've seen, that has added those resistors. I have been running successfully, without them. I occasionally would see some dimming, but, I believe that had more to do with my power source. I am concerned, if I add these resistors to something that isn't broken.. it could cause problems.
Any thoughts on their value? Perhaps a few key resistors might be more effective than others? The device is being driven by an ESP32, which has some built-in line resistance, and the TFT board itself has 6 visible resistors on it. So, perhaps that explains why I haven't needed them?
Also, I have some 22uF and 10uF caps near the power and the processor.. but has anyone had any success stabilizing screens like these by putting a cap near the power to the TFT too? If so, what size has shown to improve stability?
Suggestions appreciated as always, thanks.
It looks like this stuff is making sense to you, great! If it works what are you going to fix? You got it when you I am concerned, if I add these resistors to something that isn’t broken. it could cause problems, that is a great assumption.
I would say they are not needed. The data tells you directly:
- Support various MCU in-line without any wiring (no resistors)
- Integrated voltage regulator IC, support 5V or 3.3V power supply (be sure to select correctly)
- Onboard level shifting scheme, truly compatible with 5V/3.3V IO level.
(not sure about pull up resistors, you may want to try some).
- Support a variety of microcontroller IO connections (should be fine)
2. Integrated voltage regulator IC, support 5V or 3.3V power supply (be sure to select correctly)
That is probably a pretty 'touchy' subject here.
The misleading thing, when testing, is that 3.3V MCU's 'sorta' work with 5V TFT power, but, only at very low pixel draw rates, I discovered. Mismatching the power of the MCU and the TFT is a sure-fire way to have strange issues with the SPI., later on Always gotta match the MCU and TFT voltages, for long-term reliability!
Aside from that, just looking to supply 'cleanest' power I can, while maintaining the life of the TFT at this point. Given how low the current draw is compared to other electronic components, I think I might just put an extra 10uF cap near the TFT power, and leave it at that. Maybe once in a blue moon, that 5 cent part will prevent screen flicker.
I think my time is better spent putting the big caps nearer the servos and other power pigs, since they can have indirect impacts on the TFT. That's sorta what I am looking into now.
Thanks for your reply!
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