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STM32F4 Discovery and SSD2119 LCD driver with the LCD_35T example

Former Member

I'm trying to loading the LCD_35T example on an STM32F4 Discovery connected to a 320x240 TFT LCD with the SSD2119 driver (connected like in the expansion board).

What I get is that I'm not able to write on all the pixels of the display. I suppose it is a problem of register initialization:

  LCD_WriteReg(SSD2119_SLEEP_MODE_1_REG, 0x0001);
  // Set initial power parameters.
  LCD_WriteReg(SSD2119_PWR_CTRL_5_REG, 0x002B);
  LCD_WriteReg(SSD2119_VCOM_OTP_1_REG, 0x0006);
  // Start the oscillator.
  LCD_WriteReg(SSD2119_OSC_START_REG, 0x0001);
  // Set pixel format and basic display orientation (scanning direction).
  LCD_WriteReg(SSD2119_OUTPUT_CTRL_REG, 0x72EF); //72-30EF
  LCD_WriteReg(SSD2119_LCD_DRIVE_AC_CTRL_REG, 0x0600);
  // Exit sleep mode.
  LCD_WriteReg(SSD2119_SLEEP_MODE_1_REG, 0x0000);
  _delay_(5);
  // Configure pixel color format and MCU interface parameters.
  LCD_WriteReg(SSD2119_ENTRY_MODE_REG, ENTRY_MODE_DEFAULT);
  // Set analog parameters
  LCD_WriteReg(SSD2119_SLEEP_MODE_2_REG, 0x0999);
  LCD_WriteReg(SSD2119_ANALOG_SET_REG, 0x3800);
  // Enable the display
  LCD_WriteReg(SSD2119_DISPLAY_CTRL_REG, 0x0033);
  // Set VCIX2 voltage to 6.1V.
  LCD_WriteReg(SSD2119_PWR_CTRL_2_REG, 0x0005);
  // Configure gamma correction.
  LCD_WriteReg(SSD2119_GAMMA_CTRL_1_REG, 0x0000);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_2_REG, 0x0303);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_3_REG, 0x0407);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_4_REG, 0x0301);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_5_REG, 0x0301);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_6_REG, 0x0403);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_7_REG, 0x0707);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_8_REG, 0x0400);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_9_REG, 0x0A00);
  LCD_WriteReg(SSD2119_GAMMA_CTRL_10_REG, 0x1000);
  // Configure Vlcd63 and VCOMl
  LCD_WriteReg(SSD2119_PWR_CTRL_3_REG, 0x000A);
  LCD_WriteReg(SSD2119_PWR_CTRL_4_REG, 0x2E00);
  LCD_WriteReg(SSD2119_GATE_SCAN_START_REG, 0x0001); // Vertical offset
  // Set the display size and ensure that the GRAM window is set to allow
  // access to the full display buffer.
  LCD_WriteReg(SSD2119_V_RAM_POS_REG, (LCD_PIXEL_HEIGHT-1) << 8);
  LCD_WriteReg(SSD2119_H_RAM_START_REG, 0x0000);
  LCD_WriteReg(SSD2119_H_RAM_END_REG, LCD_PIXEL_WIDTH-1);
  //LCD_WriteReg(SSD2119_H_PORCH, 0x001D);
  //LCD_WriteReg(SSD2119_V_PORCH, 0x0003);
  //LCD_WriteReg(SSD2119_FW_START, 0x0000);
  //LCD_WriteReg(SSD2119_FW_END, 0x00EF);
  //LCD_WriteReg(SSD2119_SW_START, 0x0000);
  //LCD_WriteReg(SSD2119_SW_END, 0x00EF);
  LCD_WriteReg(SSD2119_X_RAM_ADDR_REG, 0x00);
  LCD_WriteReg(SSD2119_Y_RAM_ADDR_REG, 0x00);
  // clear the lcd
  LCD_WriteReg(SSD2119_RAM_DATA_REG, 0x0000);

The strange thing is that if I configure the SSD2119_H_RAM_END_REG [0x46] to be between 0 and 255 the display becomes wider but the last 65 pixels (320-255) are overwritten in the first pixels, like in the first two images. If I configure the same register to be greater than 255 (up to 320) the display shows just the last 65 pixels leaving undefined the rest of the display area.

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  • 0

    Hi gvol,

    do you have original  STM32F4DIS-BBSTM32F4DIS-BB and  STM32F4DIS-LCDSTM32F4DIS-LCD For me this demo works fine I can send you my HEX file to try out Is there any particular reason you changed value loaded to SSD2119OUTPUTCTRLREG from 0x30EF to 0x72EF

  • 0

    Hi,

     

    I had quite similar symptom with an SSD1289 and a PSoC, in my case I was trying to write the memmmory of the LCD too fast.

    You can check the hex file if using the ST boards (or if using the same pin out).

    You could also check with him if clock configuration in the same.

    Other easy check from you side to discard timing issue, is compile your code with a much slower timing configuration.

     

    Hope that helps

  • 0 in reply to kulky64

    Hi,

    I'm using an homemade expansion board with the same pinout, while the LCD is not the STM32F4DIS-LCDSTM32F4DIS-LCDbut one with the same SSD2119 driver .

    Could you send me your HEX to try what it does?

    The value of SSD2119_OUTPUT_CTRL_REG has been changed to rotate the screen; it works fine as I desire but does not solve the problem even with the previous value.

  • 0 in reply to gihu

    Hi ,

    you or have any idea in how I could change the writing speed on the memmemory of the LCD?

    Kulky64 did you changed something in the clock configuration? Because I'm using the predefined values in the project without any modification.

     

    Thanks both

  • 0 in reply to Former Member

    Hi,

    if you have different LCD, then i'm affraid my hex will not help you much. The SSD2119 driver may be the same, but for different display the correspondence between controller's GDDRAM and physical dot matrix may be different, so you have to tweak some registers to accomodate this. I have just compiled the provided example and for me it worked without any modifications.

  • 0

    SOLVED!,

    the problem both in the registry setting and in the default font.

     

      LCD_WriteReg(0x0028,0x0006);    // VCOM OTP
  LCD_WriteReg(0x0000,0x0001);    // start Oscillator
  LCD_WriteReg(0x0010,0x0000);    // Sleep mode
  LCD_WriteReg(0x0001,0x72EF);    // Driver Output Control
  LCD_WriteReg(0x0002,0x0600);    // LCD Driving Waveform Control
  LCD_WriteReg(0x0003,0x6A38);    // Power Control 1
  LCD_WriteReg(0x0011,0x6270);    // Entry Mode Horizontal screen mode 320*240 65k colour
  LCD_WriteReg(0X000F,0x0000);    // Gate Scan Position
  LCD_WriteReg(0X000B,0x5308);    // Frame Cycle Control
  LCD_WriteReg(0x000C,0x0003);    // Power Control 2
  LCD_WriteReg(0x000D,0x000A);    // Power Control 3
  LCD_WriteReg(0x000E,0x2E00);    // Power Control 4
  LCD_WriteReg(0x001E,0x00BE);    // Power Control 5
  LCD_WriteReg(0x0025,0x8000);    // Frame Frequency Control
  LCD_WriteReg(0x0026,0x7800);    // Analog setting
  LCD_WriteReg(0x004E,0x0000);    // Ram Address Set
  LCD_WriteReg(0x004F,0x0000);    // Ram Address Set
  LCD_WriteReg(0x0012,0x08D9);    // Sleep mode
  LCD_WriteReg(0x0030,0x0000); // Gamma Control (R30h to R3Bh)
  LCD_WriteReg(0x0031,0x0104);
  LCD_WriteReg(0x0032,0x0100);
  LCD_WriteReg(0x0033,0x0305);
  LCD_WriteReg(0x0034,0x0505);
  LCD_WriteReg(0x0035,0x0305);
  LCD_WriteReg(0x0036,0x0707);
  LCD_WriteReg(0x0037,0x0300);
  LCD_WriteReg(0x003A,0x1200);
  LCD_WriteReg(0x003B,0x0800);
  LCD_WriteReg(0x0007,0x0033);    // Display Control
  LCD_WriteReg(0x0022,0x0000);   // RAM data write/read */

     

    After this setting if I set the font to a smaller size like Font12x12 instead of Font16x24 it works. Keeping the Font16x24 is able to clear all the display, removing the undefined area, but the problem in the string overwriting still exists.