st7789h2 LCD MODULE issues

[MRedd.3]

hello sir,

My self-Mahesh firmware engineer

Currently I am working with 1.54 inch display module(st7789h2),This module is configured with four wire SPI.

I am facing some issues

1, Pixel writing is very slow.

2, Not able to control the brightness.

3, I am able to write only full image(240*240)

Pixel writing is very slow:

I am able to display the test and image, however writing speed is very slow ,to write full image (240 *240) pixel its taking around 4min. we tried to change frame rate value (00 to FF )in C6h register ,still pixel writing speed remains same. Please find the attached video file you can see the how the pixel writing.

Kindly let me know how to increase the pixel speed.

Not able to control the brightness:

We are setting the BCTRL bit to enable the brightness control blank in 53h register, Display control register (51h) DBV0-7 value we tried to change it from min to max ,however brightness remains same. Any other register need to be set.

I am able to write only full image(240*240):

To get bitmapping image data(16bit) I am using LCD image converter tool. When we tried to write full image( 240*240) its displaying properly,

but when we tried to write 100 *100 Pixel it’s not displaying as expected.

anyone have any idea please help to resolve this issue

Thanks & Regards,

Mahesh

[MM..1]

void spi_write(const uint8_t * data, uint8_t size)
{
   spi_xfer_done=false;
    APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi,data,size,NULL,0));
    while(spi_xfer_done == false){};
}

 uint8_t write_2byte_data(uint16_t value)
{
  uint8_t data[2];
  uint16_t n_data_byte=2;
  data[0]=(uint8_t*)(value>>8);
  data[1]=(uint8_t*)(value);
  nrf_gpio_pin_set(ST7735_DC_PIN);
  spi_write(data, n_data_byte);
}

This isnt good, read nrf SPI docu and too nrf_gpio_pin_set speed. Move this before for image and call only once

too this data mix is bad idea clean this code.

[MRedd.3]

Good day, I fixed the problem, and now I can write a full image quickly.

The st7789h2 device has a frame pin for tearing signal effect to synchronize the mcu to frame memory. I haven't used it yet, but without it correct image displaying.

Is it necessary to use that pin? Is that required for future implementations, or can I leave this pin unconnected in the schematics?

Thanks