NHD-3.5-320240MF-ATXL#-T-1

[adrianzambrano]

Good afternoon, I am currently working with NHD-3.5-320240MF-ATXL#-T-1 TFT LCD Display module, and I cannot find the information regarding how many pixel clock cycles are allowed per horizontal line, neither the specific Horizontal Sync back porch and front porch or Vertical Sync back porch and front porch. I couldn't find this info in the product datasheet and I would really appreciate your support in this matter.

The pixel clock frequency I am using is 6,85714 MHz

Best regards

[Michael_L]

Have you accessed the NT39016D driver datasheet (from the link at the bottom of page 5 of our display datasheet)?  This is the document you should refer to for further details about our display and how its driver works.  Here is a table of values that should work for you:

         PARAMETER                   VALUE
Horizontal Front Porch         70 CLKIN
Horizontal Back Porch          18 CLKIN
Horizontal SYNC Width        Min. 24ns
Vertical Front Porch              13 CLKIN
Vertical Back Porch               10 CLKIN
Vertical SYNC Width             Min. 24ns
Pixel Clock Frequency            6.4 MHz

[adrianzambrano]

Yes, I checked out the datasheet of the driver, but the only information I found was that the operating frequency of the device for a 24 bit RGB Mode is strictly 6.4 MHz with a HSYNC period (Th)of 408 CLKIN in a time range between 60 usec to 67 usec (Page 26 - Data Active Area and Page 30 - HSD period time), but there is no more information about the implementation of a CLKIN frequency different than 6.4 MHz for a 24 bit RGB Mode, neither the info regarding HSYNC front porch / back porch or VSYNC front porch/ back porch.

In my design, the fixed CLKIN frequency provided to the driver is 6.86 MHz, so it means it is incorrect for the proper use of the device? what is the range of CLKIN frequency allowed by the device? is my design limited to a HSD period time (Th) between 60 usec to 67 usec or are those limitations valid just for a specified CLKIN frequency?

Can you lead me to know how did you get the info regarding to the following data (in the link http://www.newhavendisplay.com/app_notes/NT39016D.pdf, it is not explicitly specified)?

         PARAMETER                   VALUE
Horizontal Front Porch         70 CLKIN
Horizontal Back Porch          18 CLKIN
Vertical Front Porch              13 CLKIN
Vertical Back Porch               10 CLKIN

[Michael_L]

You should be fine with 6.86MHz.  Have you tried these values?  Does the display work?
I got those values from the datasheet on page 35.  There is a diagram that illustrates the porch values.
My apologies, the vertical porch values are supposed to be LINES not CLKIN.
For the horizontal front porch, you can see it says default 70.  Then for the back porch you have total area = 408, active area = 320, and front porch = 70.
Therefore, 408 - 320 - 70 = 18.
For the vertical front porch, it says default 13.  For the back porch it says total lines = 263, display lines = 240, and front porch = 13.
Therefore, 263 - 240 - 13 = 10.

[adrianzambrano]

Thank you very much for the information

I haven't tried those values yet, because I thought that with a CLKIN frequency of 6.86 MHz (CLKIN = 145.8ns) for a horizontal line (408*CLKIN = 59,475 us) is out of the range specified in the page 30 (HSD period time : 60us-67us).

Is it ok to have a HSD period time of 59,475 us?

[Michael_L]

You are very welcome! I would think it would still work, but the only way to know for sure is to try it. 
Let us know how it goes!