Mcufriend_kbv.cpp - begin instruction - ST7793

Using Arduino Displays
1

I have some questions about the begin function in the file mcufriend_kbv.cpp for the ST7793 driver (line 2937 - #if defined(SUPPORT_B509_7793).

  1. What is the purpose of writing 0X000 four times in the register 0x0000. I don't understand, I thought this is the ID register and read only?
  2. The 'gamma' registers are labeled 0X0300 etc while in the data sheet of the diver, I find the addresses 0X0380 etc.
  3. When I write these values in these registers and read them again, I get different values. Also after a reset, I do not read the default values?
  4. Is the order that is used to initiate these registers important?

I would like to understand this better. I am using a different type of hardware set up (A basic xiao board for the RS, RD, WR, ... lines and a I2C pcf8574 expansion IC for the Data line.

Thanks for your help.

2

I forgot to mention that I can read the ID correctly 7793. So I suppose that my reading and writing function are correctly programmed.

3

Hi and welcome!

The Author of the library you use is no longer among us, unfortunately.
So you may not get a founded answer to your questions.

I suggest you look at the source of some other library, e.g.
Arduino_GFX/src/display/Arduino_ST7789.cpp at master · moononournation/Arduino_GFX · GitHub

Oops, this is for a different controller, doesn't support ST7793.

Then you might search for ST7793 in this forum / section.