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I am searching for an explanation for the coding idiom for changing TFT display resolution that is used in the PORT from mcufriend’s Arduino code.

init_table16(R61509V_regValues, sizeof(R61509V_regValues));

  1. p16 = (int16_t *) & _height;
  2. *p16 = 400;

Statements 1 and 2 are to adjust the vertical resolution. I do understand this.

  1. p16 int16_t* 0x2000000c<_height> To allocate memory for _height in STM32F103 SRAM (64 KB aliased by bit-banding)

  2. To assign value (400) to the location.

Now the magic has happened and the resolution of the ST7793 has been adjusted over the parallel interface.

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    \$\begingroup\$ the URL is broken \$\endgroup\$ Commented Aug 13, 2022 at 17:00
  • \$\begingroup\$ what is your specific question? ... I am searching for... is not a question \$\endgroup\$ Commented Aug 13, 2022 at 17:12
  • \$\begingroup\$ whether you are asking for a place where the information can be found or you are asking for an explanation, your post is about programming and belongs at stackoverflow.com/questions \$\endgroup\$ Commented Aug 13, 2022 at 17:18
  • \$\begingroup\$ Your line #1 does not allocate any memory to anything. It assigns the value of the address of the _height variable to the pointer variable p16. Without more context it's not clear to me why both line couldn't have been simple combined into _height = 400;. \$\endgroup\$ Commented Aug 13, 2022 at 18:03
  • \$\begingroup\$ The _height variable does not directly involve to sending a command over 8080 parallel port to the ST7793 chip. How does variable _height affect the resolution? This is a question. \$\endgroup\$ Commented Aug 13, 2022 at 21:11

1 Answer 1

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The statement p16 = (int16_t *) & _height; is giving access to bit-banding memory. *p16 = 400; is setting individual bits to peripheral registers mapping to a bit-banding region of M3 memory. This is how a miracle is created. I will spend the rest of my life learning the black magic of computing and sharing my experience. Thank you for your support.

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