Newhaven Display Forum

Sorry I was not clear.  I have  a 1 ohm resistor on main 3.3V regulator for the whole board.  I can set the back light to draw 25mA, 100mA or I can turn the backlight off.  With the backlight off, but the LCD connected and initialized, I am measuring 97mA draw for the entire board.  Then I remove the LCD and measure the current again and I get roughly the same 97mA (the difference is in the noise).  It seams like the LCD is not drawing any current or it is drawing less then 1mA.  I have two board I have test the LCD on each board and have swaped the LCD between boards and they act the same.

I also opened the LCD connector and measured from the pin that contacts the LCD flex cable to the pad on my PCB and found them all making a good connection.

In the datasheet is days that for 8-bit parallel communication we should use DB8-DB15.  Is that correct (as shown in my schematic)?  The LCD is behaving as though it is not getting anything at all.  I disabled the init routine briefly just to see what it would do and I got the same display, all white.

I verified that the value I write to the data port shows up on the pins to the LCD.

Then I wrote the following code but did not get any green (or any changed) pixels.

   // Define an area of 100 Pixels
   LCD_CMD(0x2A);               // Column Address
   LCD_ARG(0x00);LCD_ARG(0x0A);   // Set Start column at pixel 10
   LCD_ARG(0x00);LCD_ARG(0x13);   // Set End column at pixel 19
   LCD_CMD(0x2B);               // Page Address
   LCD_ARG(0x00);LCD_ARG(0x0A);   // Set Start row at 10
   LCD_ARG(0x00);LCD_ARG(0x13);   // Set End row at 19

   // Turn the area defined from white to green
   LCD_CMD(0x2C);
   for (i=0; i<100; i++)   // write out 100 values
      {
         LCD_ARG(0x07);   // Set color to green
         LCD_ARG(0xE0);   
      }   

Here is a link to the connector that I am using to attach the LCD to the board: http://www.digikey.com/product-detail/en/FH28-40S-0.5SH(05)/HFV140CT-ND/2119015.  It is a 40 Pin Bottom contact 0.020" pitch.

The display is basically white. There are no colors.  Nothing is ever displayed on the screen.  I have gone through the code I am using again and very carefully compared it to the code you said works.  I think it is the same but I am going to put down my code here so I am being clear as to what I am doing.


Setting up the ports is done in MCU initialization and is not shown.

In main.c  the backlight is turned on and the LCD initialized
// Set up LCD
  LCD_BACKLIGHT_ON;
  init_lcd();

Then the program loops forever waiting for a command from the user. In this case the letter ‘L’.
//=======================================================
//LCD
//=======================================================

else if (c == 'L'|| c == 'l')
{
   putstring1("Write blue and green to screen then loop\n");
   putstring1("Power cycle to exit\n");
   loopL:
   display();
   waitsome(1000);
   goto loopL;
}



This is the wait routine.  Millisecond counter, but even ms only:
void waitsome (uint16_t lev)
{
   // Each count is 2 ms; e.g. lev=50 is 100ms.
   // Write lev as the ms you want let the code divide by 2
   extern uint16_t P;
   P=0;
   while (P< (lev/2));// 2 ms/count
 
}

Write a command:
// Write a command to the LCD Controller
void LCD_CMD (uint8_t cmd)
{
  LCD_DC0;            // This is a Command
  LCD_DATA_SET(cmd);   // Command index
  LCD_WR0;
  LCD_WR1;            // Data latched on rising edge
     // (8080 parallel interface). Minimum data setup and hold time is
        // 10ns and 15ns respectively. Shouldn't need NOP through 100 MHz
      // unless capacitance is high (>30pF) on data bus/control lines
  LCD_DC1;            // Default to argument/data      
}

Write data:
// Write byte argument (arg) to LCD controller
void LCD_ARG(uint8_t arg)
{
  LCD_DC1;            // This is an Argument/data
  LCD_DATA_SET(arg);   //  Argument put on data lines
  LCD_WR0;
  LCD_WR1;            // Data latched on rising edge
}

This writes the blue and green to memory:
void display(void)
{
   uint16_t i;
   LCD_CMD(0x2C);   // Begin writing to frame memory
   for (i=0; i<38400; i++)   // fill screen with blue pixels
   {
      LCD_ARG(0x00);
      LCD_ARG(0x1F);
      LCD_ARG(0x00);
      LCD_ARG(0x1F);
   }
   for (i=0; i<38400; i++)   // fill screen with green pixels
   {
      LCD_ARG(0x07);
      LCD_ARG(0xE0);
      LCD_ARG(0x07);
      LCD_ARG(0xE0);
   }
}


Here is the initialization code:
void init_lcd(void)
{
  putstring1("\nInitializing LCD\n");
  GPIO[(GPIO_PORTA + GPIO_OVRC) >> 2] = NH_CS; // Clear chip select (make active)
  LCD_RD1;      // Not doing a read so make sure it's high
  LCD_WR0;
  LCD_RESET0;
  waitsome(250);
  LCD_RESET1;
  waitsome(250); 
 
  // New routine
  LCD_CMD (0x28);   // Display OFF
  LCD_CMD(0x11);   // exit sleep mode
 
  LCD_CMD(0xCB);   // Power Control A
  LCD_ARG(0x39);   //
  LCD_ARG(0x2C);   //
  LCD_ARG(0x00);   //
  LCD_ARG(0x34);   // Vcore=1.6V
  LCD_ARG(0x02);   // DDVDH=5.6V
 
  LCD_CMD(0xCF);   // Power Control B
  LCD_ARG(0x00);   //
  LCD_ARG(0x81);   // PCEQ off
  LCD_ARG(0x30);   // ESD protection
 
  LCD_CMD(0xC0);
  LCD_ARG(0x26);   // Power Control 1
  LCD_ARG(0X04);   // second parameter for ILI9340 (ignored by ILI9341)
 
  LCD_CMD(0xC1);   // Power control 2
  LCD_ARG(0x11);   //
 
  LCD_CMD(0xC5);   // VCOM control 1
  LCD_ARG(0x35);   //
  LCD_ARG(0x3E);   //

  LCD_CMD(0x36);   // memory access control=BGR
  LCD_ARG(0x88);   //

  LCD_CMD(0xB1);   // Frame rate control
  LCD_ARG(0x00);   //
  LCD_ARG(0x18);   //

  LCD_CMD(0xB6);   // display function control
  LCD_ARG(0x0A);   //
  LCD_ARG(0xA2);   //

  LCD_CMD(0xC7);   // VCOM control 2
  LCD_ARG(0xBE);   //
 
  LCD_CMD(0x3A);   // pixel format = 16 bit per pixel
  LCD_ARG(0x55);   //

  /*LCD_CMD(0xE0);   // Positive gamma correction
  LCD_ARG(0x1F);
  LCD_ARG(0x1B);
  LCD_ARG(0x18);
  LCD_ARG(0x0B);
  LCD_ARG(0x0F);
  LCD_ARG(0x09);
  LCD_ARG(0x46);
  LCD_ARG(0xB5);
  LCD_ARG(0x37);
  LCD_ARG(0x0A);
  LCD_ARG(0x0C);
  LCD_ARG(0x07);
  LCD_ARG(0x07);
  LCD_ARG(0x05);
  LCD_ARG(0x00);

  LCD_CMD(0xE1);   // Negative gamma correction
  LCD_ARG(0x00);
  LCD_ARG(0x24);
  LCD_ARG(0x27);
  LCD_ARG(0x04);
  LCD_ARG(0x10);
  LCD_ARG(0x06);
  LCD_ARG(0x39);
  LCD_ARG(0x74);
  LCD_ARG(0x48);
  LCD_ARG(0x05);
  LCD_ARG(0x13);
  LCD_ARG(0x38);
  LCD_ARG(0x38);
  LCD_ARG(0x3A);
  LCD_ARG(0x1F);*/

  LCD_CMD(0xF2);   // 3G Gamma control
  LCD_ARG(0x02);   // off

  LCD_CMD(0x26);   // Gamma curve 3
  LCD_ARG(0x01);   //
 
  LCD_CMD(0x2A);   // column address set
  LCD_ARG(0x00);   //
  LCD_ARG(0x00);   // start 0x0000
  LCD_ARG(0x00);   //
  LCD_ARG(0xEF);   // end 0x00EF (240)

  LCD_CMD(0x2B);   // page address set
  LCD_ARG(0x00);   //
  LCD_ARG(0x00);   // start 0x0000
  LCD_ARG(0x01);   //
  LCD_ARG(0x3F);   // end 0x013F (320)
 
  LCD_CMD(0x29);   // Turn on Display

  waitsome(10); 
}

That is all of it.

Yes,  I can adjust the brightness of the backlight using the two transistors.  Yesterday I ohmed out all the grounds at the connector and then measured all the power lines. Every connection looks like it is good.  Do you have any suggestions on what I could try?

I changed the code to match, very closely, to the code you posted.  I also matched the timer/delay (I am assuming that the number represents milliseconds).  I still do not get any response (any change visually) from the display.    I thought maybe I had wired it wrong.  So I checked the pinout on the data sheet against my schematic and it is the same.  Then I verified that I can change each of the following signals (to make sure there was not a break in the pcb): CS, DC, WR, RD, RST, D0:D8.  They all responded.  I checked this on the connector going to the display.

I have attached a shot of the schematic.  Is it hooked up as you would expect?  I don't really know where to go from here.  I have two identical boards and they both are acting the same way, with the same version of code loaded.

[attachment deleted by admin]