Author Topic: NHD-5.0-800480TF-ATXL#-CTP why don't typical timing values work?  (Read 2686 times)

jkelleher

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I have a Beagle Bone Black, and looking to use the NHD-5.0-800480-ATXL with Android(Linux) source code that I found on the Internet.  When I use the timings from the internet:
   /* NewHaven - NHD-5.0-800480TF-ATXL-CTP */
        [13] = {
                .name = "NHO-5.0-800480TF",
                .width = 800,
                .height = 480,
                .hfp = 39,
                .hbp = 39,
                .hsw = 48,
                .vfp = 32,
                .vbp = 32,
                .vsw = 3,
                .pxl_clk = 45000000,
                .invert_pxl_clk = 1,
        },

The display looks ok, but not great (a white line at the top)

and then run using the Typical values in the datasheet, which I thought would provide a better fit for the display:
   /* Newhaven NHD-7.0-800480TF-ATXL#-CTP */
   [11] = {
      .name = "NHD-5.0-800480TF",
      .width = 800,
      .height = 480,
      .hfp = 40,
      .hbp = 88,
      .hsw = 48,
      .vfp = 13,
      .vbp = 32,
      .vsw = 3,
      .pxl_clk = 40000000,
      .invert_pxl_clk = 1,
   },

We get an awful picture, it's readable, but shifted quite a few pixels to the right, and the gradients are hard wide lines.

Why doesn't the data sheet typical values look so bad.  How does one go about on getting the right values, I'm guessing the datasheet to the actual display driver IC would hopefully give better information?

So my question is, where am I supposed to get timing values for the best looking display, without testing the almost infinite parameters possible in the min/max data sheet recommendations?

I saw a few questions on the forum where someone posts what processor/board they are using with which display, and asks for timing.  Is this the best way, if so, I have a Beagle Bone Black and the NHD-5.0-800480-ATXL-CTP, what values should I use for:   .width = 800, .height = 480, .hfp = ?,  .hbp = ?, .hsw = ?,  .vfp = ?, .vbp = ?, .vsw = ?, .pxl_clk = ?, .invert_pxl_clk = ?

Thanks,
Jim

Paul_B

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Re: NHD-5.0-800480TF-ATXL#-CTP why don't typical timing values work?
« Reply #1 on: July 24, 2015, 11:41:28 AM »
Hi Jim,

Sounds like a fun project!

The timing values listed above are perfectly acceptable, I would like to see your boot process if possible.

To see the actual boot process a RS232 cable like the TTL-232R-3V3 from FTDI is needed. Just plug it into the J1 connector and open a serial terminal of your choice.

Finally, post the terminal output on the forum so we can start debuging  8)


jmag999

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Re: NHD-5.0-800480TF-ATXL#-CTP why don't typical timing values work?
« Reply #2 on: August 31, 2015, 05:08:45 AM »
Did you ever solve this?  I am having the same issue.

 

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