I have two different noise sources, one I assume is from the power supply but it is very low. I have a 2nd issue with a lot more noise (hum/buzz, video with noise below) coming from a TFT display connected via SPI. This is not my area and wanted to see if anyone has run into this before. I thought it was the backlight but its the chipset 3.3V that seems to be the cause it. I'm using the Teensy 4.0x hat but I had to solder jumpers from it to a breadboard to test. Removing the 5V and GND for the backlight does not change anything, as soon as the 3.3V is removed the noise stops, backlight on with no 3.3V chipset connected, no noise. Not sure how to go about filtering this? I added some extra caps on the 3.3V output from the teensy, no change. Tried driving with a separate 3.3V supply, no change, separate 3.3 volt with caps no change. Powered with a bench top regulated power supply , no change. A 2nd switch mode 5V power I had lying around did not help either. I have seen some PT8211 using output drivers, but I assume that will just boost the noise. It's possible its noise from the breadboard, I gave everything the wiggle test to but made no difference. I tried a 2nd 4.1 and a second brand new display, no change. Note, I have the trace cut so I can use the USB with the bench supply, disconnecting USB does not change anything. Open to any advice.
Example Video: https://vimeo.com/694191704
Display: https://newhavendisplay.com/5-0-inch-premium-eve2-resistive-tft/
Display Datasheet: https://store-ybeckn7x79.mybigcommerce.com/content/specs/NHD-5.0-800480FT-CTXL-T.pdf
Example Video: https://vimeo.com/694191704
Display: https://newhavendisplay.com/5-0-inch-premium-eve2-resistive-tft/
Display Datasheet: https://store-ybeckn7x79.mybigcommerce.com/content/specs/NHD-5.0-800480FT-CTXL-T.pdf
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