Getting started with NHD-2.4-240320SF-CTXI#-FT1

[sean]

Yes.  I have two identical boards.  They both behave the same, that is I only get a white screen that does not change when I run the code.  I have tried a few things.  I swapped the display between the two boards with no change.  I was talking to a friend who thought it might be a timing issue during the init routine.  So I have placed a 250ms delay after each command  ( command, arguments, delay, next command).  That did not change anything except make the initialization take much longer.

I think I am so close to making this work. I feel like a am missing some small detail and have no idea how to get past this roadblock.

[Michael_L]

You said you code loops forever until it gets a user input of an "L"; are you providing this input?  Can you just try writing pixels of any color to the display without the loop?

[sean]

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);   
      }   

[Michael_L]

Can you try grounding the /CS line?

[sean]

I hard wired the CS line to ground.  Same result.  I also rechecked my code against the know good code and did not find any inconsistencies.

[sean]

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.

[sean]

I measured the current draw of the board with the backlight off and with the LCD disconnected and I do not see a change.  It seams the current change should be 7-9mA.

[Michael_L]

That is odd, it sounds like something is wrong with your board.  I'm not sure what, possibly you are exceeding the output current rating and therefore your code isn't really running on your processor? (Since you said the current is not changing at all with the backlight on or off).  I'm assuming you are powering the display with 3.3V, and using 3.3V logic?
Is there a way you can try using the display with a different board/MCU?  The code I sent you works, and your connections are correct, and the speed of your micro is not too fast.  This is the only thing I can suggest you try at this point.

I highly doubt the displays are defective, but you may email nhtech@newhavendisplay.com to set up an RMA if you would like to return the displays to us for analysis.

[sean]

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.

[brybot]

EDIT: Fixed. Please ignore.

Was this ever resolved? I'm experiencing the same issue. I'm sending commands to the display, but nothing happens. The backlight is on, and the screen is blank. I'm using the example code on the website. Reading through this thread, I seem to be experiencing the same issues (although I haven't checked the current draw). I've tried two LCDs and two hardware platforms. Any help would be appreciated!

[sean]

brybot,

We have not fixed it yet.  We have turned it over to someone to review the design and debut the project.  As of yet they have not discovered the problem either.  You said you have fixed your problem.  Would you mind explaining what was happening and how you solved the problem. Perhaps it will help us solve our problem.  Thanks.

Sean

[brybot]

Hi Sean,

My problem was that when I copied the example code, I had misinterpreted one of the signals, RS, as RESET. As soon I corrected that signal my problem was resolved.