st7735 dead pixel when setRotation(2)

[chaabanihoussem]

Hi,

I'm using T-dongle-S3 with ST7735 screen
Screen works fine with setRotation(0), setRotation(1), setRotation(3) but some pixels are dead when setRotation(2)

have you tested this before?
Any idea how to fix this?

Thanks

[tobozo]

hi,

thank you for testing this

fixing a problem requires to know what the problem is, symptoms and assumptions aren't enough

please provide more information such as your LGFX configuration, a picture of the build and anything that can help reproduce the issue

[chaabanihoussem]

/* ----------------------*/
class LGFX_LiLyGo_TDongleS3 : public lgfx::LGFX_Device
{
  lgfx::Panel_ST7735S _panel_instance;
  lgfx::Bus_SPI       _bus_instance;
  lgfx::Light_PWM     _light_instance;

public:
  LGFX_LiLyGo_TDongleS3(void)
  {
    {
      auto cfg = _bus_instance.config();

      cfg.spi_host    = SPI3_HOST;              // SPI2_HOST is in use by the RGB led
      cfg.spi_mode    = 0;                      // Set SPI communication mode (0 ~ 3)
      cfg.freq_write  = 27000000;               // SPI clock when sending (max 80MHz, rounded to 80MHz divided by an integer)
      cfg.freq_read   = 16000000;               // SPI clock when receiving
      cfg.spi_3wire   = true;                   // Set true when receiving on the MOSI pin
      cfg.use_lock    = false;                  // Set true when using transaction lock
      cfg.dma_channel = SPI_DMA_CH_AUTO;        // Set the DMA channel to use (0=not use DMA / 1=1ch / 2=ch / SPI_DMA_CH_AUTO=auto setting)

      cfg.pin_sclk    = DISPLAY_SCLK;           // set SPI SCLK pin number
      cfg.pin_mosi    = DISPLAY_MOSI;           // Set MOSI pin number for SPI
      cfg.pin_miso    = DISPLAY_MISO;           // Set MISO pin for SPI (-1 = disable)
      cfg.pin_dc      = DISPLAY_DC;             // Set SPI D/C pin number (-1 = disable)

     _bus_instance.config (cfg);                // Apply the setting value to the bus.
     _panel_instance.setBus (&_bus_instance);   // Sets the bus to the panel.
    }

    {
      auto cfg = _panel_instance.config();      // Obtain the structure for display panel settings.

      cfg.pin_cs   = DISPLAY_CS;                // Pin number to which CS is connected (-1 = disable)
      cfg.pin_rst  = DISPLAY_RST;               // pin number where RST is connected (-1 = disable)
      cfg.pin_busy = DISPLAY_BUSY ;             // pin number to which BUSY is connected (-1 = disable)

      cfg.panel_width       = DISPLAY_HEIGHT;   // actual displayable width. Note: width/height swapped due to the rotation
      cfg.panel_height      = DISPLAY_WIDTH;    // Actual displayable height Note: width/height swapped due to the rotation
      cfg.offset_x          = 26;               // Panel offset in X direction
      cfg.offset_y          = 1;                // Y direction offset amount of the panel
      cfg.offset_rotation   = 1;                // Rotation direction value offset 0~7 (4~7 are upside down)
      cfg.dummy_read_pixel  = 8;                // Number of bits for dummy read before pixel read
      cfg.dummy_read_bits   = 1;                // Number of dummy read bits before non-pixel data read
      cfg.readable          = true;             // set to true if data can be read
      cfg.invert            = true;
      cfg.rgb_order         = false;
      cfg.dlen_16bit        = false;            // Set to true for panels that transmit data length in 16-bit units with 16-bit parallel or SPI
      cfg.bus_shared        = true;             // If the bus is shared with the SD card, set to true (bus control with drawJpgFile etc.)

      // Please set the following only when the display is shifted with a driver with a variable number of pixels such as ST7735 or ILI9163.
      cfg.memory_width  = 132;                  // Maximum width supported by driver IC
      cfg.memory_height = 160;                  // Maximum height supported by driver IC

      _panel_instance.config(cfg);
    }


    {
      auto cfg = _light_instance.config();

      cfg.pin_bl      = DISPLAY_LEDA;           // pin number to which the backlight is connected
      cfg.invert      = true;                   // true to invert backlight brightness
      cfg.freq        = 12000;                  // Backlight PWM frequency
      cfg.pwm_channel = 7;                      // PWM channel number to use

      _light_instance.config(cfg);
      _panel_instance. setLight (&_light_instance);
    }

    setPanel (&_panel_instance);
  }
};

LGFX_LiLyGo_TDongleS3 lcd;

[chaabanihoussem]

[tobozo]

driver seems correct but some models may vary, I'd play with some of those settings just to see what happens:

  cfg.memory_height = 162; // any reason why it was set to 160?

poking with the offset rotation and see how it affects the symptoms:

  cfg.offset_rotation   = 0; // does changing this also change the orientation in "dead pixel" situation ?

who knows what can happen when one pixel line has a negative offset 😉

  cfg.offset_y          = 0; tried to change this to zero?

[chaabanihoussem]

Thanks mate, works fine now, just the set rotation has shifted, what was 2 is now 3

thanks for your help