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LCD driver NT75451 issue using SPI interface

Caleg
Prodigy 90 points


Hi there

I'm trying to interface my Cortex M (Stellaris launchpad) to a small display that uses the NT75451 SPI interface.

However, I'm stuck with it because the display remains black.

As a base project I used the glcd library (http://agock.com/software/glcd-graphic-lcd-library/). This library has an implementation to the NT75451 with a parallel interface.

At init I setup the display with the sequence below; however, I'm not sure at all about it since my display has a very poor documentation...

Any idea what the problem could be? Wrong initialization?

Thanks for your help

----

GLCD_RESET_LOW();  // Display RESET line low
delay_ms(GLCD_RESET_TIME); // 1 ms delay
GLCD_RESET_HIGH();
glcd_command(0xE2); /* S/W RESET OK */
glcd_command(0xA2); /* LCD bias OK */
glcd_command(0xA0); /* ADC select OK */
glcd_command(0xC0); /* SHL Normal ?? */
// glcd_command(0x81); /* Ref vg select mode */
glcd_command(0x2F); /* Power control ?? */
glcd_command(0x22); /* reg resistor select ?? */
// glcd_command(0x8F); /* Ref vg select mode */
glcd_command(0xAF); /* Display ON */

The glcd_command() function correspond to a spi_write() with the A0 line low

-----

  • 0
    Intellectual 965 points

    Hi,

    You can use the following commands to initialise 

    glcd_write_cmd(par, 0xE2); /* S/W RESWT */
    glcd_write_cmd(par, 0xA0); /* ADC select */
    glcd_write_cmd(par, 0xC8); /* SHL Normal */
    glcd_write_cmd(par, 0xA3); /* LCD bias */
    glcd_write_cmd(par, 0x2F); /* Power control */
    glcd_write_cmd(par, 0x22); /* reg resistor select */
    glcd_write_cmd(par, 0x40); /* Initial display line 40 */
    glcd_write_cmd(par, 0xA4); /* Normal display a4 */
    glcd_write_cmd(par, 0xA6); /* Reverce display a7 */
    glcd_write_cmd(par, 0x81); /* Ref vg select mode */
    glcd_write_cmd(par, 0x3f); /* Ref vg reg select */
    glcd_write_cmd(par, 0xB0); /* Set page address */
    glcd_write_cmd(par, 0x10); /* Set coloumn addr MSB */
    glcd_write_cmd(par, 0x00); /* Set coloumn addr LSB */
    glcd_write_cmd(par, 0xAF); /* Display ON */

    Make A0 line high for writing data and make it low for writing commamd 

    Thanks

  • 0 in reply to Shinu Mary Varghese
    Prodigy 90 points

    Hmmm...

    The display is still black... I need to check the HW again ...

    Thanks!