Cannot readPixel with 3.5" TFT display, even with added tri-state buffer

KrisKasprzak

Well-known member
All,

I'm using a Teensy 3.2 and a 3.5 ILI9488 screen, and i have this display and tested the MISO line from the display and sure enough it's not tri-state. Meaning I could not get the display AND the on-board SD car working. Note, by visual inspection, it looks like I do have a MISO trace for the display.

Per the suggestions on Pauls "better tri-state design", i connected a 74AHC1G125 to the displays MISO line (controlling with the displays chip select), and viola the SD cards NOW works with the display (of course replacing the 3 SD card resistors with 0 ohm resistors. I have also tested the touch, and It works as well.

I'm dying to use my PrintScreen code to, print the screen, but the getPixel(), returns nothing. I poked around the getPixel method in the library and the code is executing but returning.

It may be in fact this display just doesn't have readPixel capability. If not, i'll just disconnect the display MISO and not use the external buffer. Bummer if this is the case.

Anyone have experience with this display?

https://www.amazon.com/gp/product/B088JWM8ZR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
 
Looks like the same displays I have purchased from a couple of EBAY sellers.

I get the impression that you can read the pixel data, but could be wrong. It has been awhile since I played with these display on a non T4.x board...

Again Sorry maybe someone else has played more with this?
 
Actually i can use all features (Display+SD+Touch), I can't read the displays MISO--hence no readPixel capability.
 
Back
Top