ST7735S display not working

[Mathan Raja]

Hi,

I am using the STM32H563 and WF18GTLAADNN0 display with SPI for interfacing and the ST7735 library from Controllerstech. However, the application is not functioning.

Could you confirm if any driver initialization steps have been omitted?

Hardware Circuit: Please note that the VDD_MCU for the circuit below is 3.3V.

To verify SPI communication:

I am using a 3-wire SPI setup.

Connection:

LCD_SDA = SPI4_MOSI

LCD_SCL = SPI4_SCK

LCD_NCS, LCD_RS, LCD_Reset = GPIO_OUTPUT

I am experiencing significant noise, making it difficult to read data on the SDA line. While executing the write command, the CS pin goes low.

To identify the data value, I toggled the CS pin during data transfer.

When I sent 0x75, I received the same value in the waveform.

thanks

Mathan

[TDK]

Why is RS toggling? Perhaps it's floating, or perhaps it's not connected to what you think it is. In any case, it shouldn't be toggling.

I don't see edges on NCS around your command. NCS should be low before the command and high after. Zoom out enough to see them and ensure they're valid.

[Mathan Raja]

Full view of CS pin & without RS toggle

[TDK]

> Full view of CS pin & without RS toggle

RS is still toggling. CS is not low during the transaction. Those are both issues. Or am I missing something here?

[Mathan Raja]

To identify the correct data transfer I made the CS pin high and Low. I will check the RS signals (Why it is toggling?). then I will come back to you. 

[Mathan Raja]

Hi, 

Here I attached the waveform after fixing the RS toggle issue. still, the LCD is not working.

ST7735_WriteCommand(0x75);

ST7735_WriteData(&dummy, sizeof(dummy));

ST7735_WriteCommand(0x97);

waveform for the above code

Thanks

Mathan

[Mathan Raja]

Hi,

ST7735_Init(0);

fillScreen(BLACK);

testAll()

while running testAll(). I got below image

;

Thanks

Mathan