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Topics - mhsqe

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TFTs / NHD-5.0-800480TF-ATXL-CTP Flickering
« on: September 07, 2015, 12:46:02 AM »
Hello,

we are currently evaluating the NHD-5.0-800480TF display and are encountering some interesting effects:

1. The display fades to white directly after writing a line. The display is written from top to bottom. The display frequency was reduced to 2MHz (ca 5 FPS) for this picture, at the normal CLK of 40 MHz this leads to a strong flickering and a dull picture. The white lines at the bottom of the picture move with the next new frame, could be related to problem 2?

2. Colors seem to alternate between every 2 frames.

3. Settings:
Controller: NXP Cortex M4 LPC4357

static const LCD_CONFIG_T NHD50TFT_LCD =
{
   .HBP = 88,                  /*!< Horizontal back porch in clocks */
   .HFP = 40,                  /*!< Horizontal front porch in clocks */
   .HSW = 48,                  /*!< HSYNC pulse width in clocks */
   .PPL = 800,                  /*!< Pixels per line */
   .VBP = 32,                  /*!< Vertical back porch */
   .VFP = 13,                  /*!< Vertical front porch */
   .VSW = 10,                  /*!< VSYNC pulse width */
   .LPP = 480,                  /*!< Lines per panel */
   .IOE = 1,                  /*!< Invert output enable, 1 = invert */
   .IPC = 1,                  /*!< Invert panel clock, 1 = invert */
   .IHS = 0,                  /*!< Invert HSYNC, 1 = invert */
   .IVS = 0,                  /*!< Invert VSYNC, 1 = invert */
   .ACB = 1,                  /*!< AC bias frequency in clocks (not used) */
   .BPP = 5,                  /*!< Maximum bits per pixel the display supports 5->24bpp*/
   .LCD = LCD_TFT,               /*!< LCD panel type */
   .color_format = LCD_COLOR_FORMAT_RGB,   /*!< BGR or RGB */
   .Dual = 0                  /*!< Dual panel, 1 = dual panel display */
};

I tested this issue with 3 displays, the only change is the intensity of the flickering. We tried to vary the timing parameters and to invert the dotclock signals but could not stop the fading.
I will try to take some good pictures of problem 2 post them later.

Any idea where to start? Thank you for your help.

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