ESP32 SPI display issue with high Frequency

[jojojijijojo]

Hi,

Im having this weird issue, if I set my CPU frequency to anything higher than 10MHz(40MHz XTAL), SPI driving an ST7735 just stops working, it freezes and glitches. If I set the CPU frequency to the lowest setting, the display works fine. I can't figure out whats the issue exactly. Im using VSPI.

Tried different displays, same problem, tried to refresh the display only 1 frame per second, same problem, 1 frame per 10 seconds same problem, reduced SPI clock speed to 10Mhz from 27mhz, same problem.

ST7735 library im using is https://github.com/Bodmer/TFT_eSPI
#define TFT_CS 5
#define TFT_RST 15
#define TFT_DC 2


Thanks!

[mikemoy]

The first thing to check is what is the max speed in MHZ that panel can receive data at.
The next thing is how long your wires are to the LCD. The longer the wires the slower you can run MHZ

[chegewara]

I don't remember now all details, but it's related to clock source in SPI and/or which SPI is used VSPI or HSPI.
I'm pretty sure you can find more info on forum if you dig a bit.