Author Topic: NHD-4.3-480800 HX8369 half pixel writes missing, resolution help  (Read 2336 times)

Steph101

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Hi,

I've looked through the posts but can't find anyone having a similar issue :(
I've been working with this LCD a while now but have finally realized why I can't display my data correctly to screen. Even though the resolution is set to 480x800, the screen is printing data as if it is 240x400.
I took the example code from the HX6389 controller datasheet (the controller attached to the LCD) which is the same as the example code for the 4.3 480x800 found on the App. Note page: http://www.newhavendisplay.com/app_notes.html.
I've double checked all the parameters in the datasheet to ensure resolution is being set correctly - and it is. The 2nd parameter following the display command 0xB2 is 0x20, which would make RES_SEL[2:0] = 010 setting the resolution to 480x800.
I also tried running the coloring screen function, which correctly changes the entire screen from red to green to blue, but it does this for 800x400 writes AND!! 400x240 writes! You can see in the example code they've used 800x240 - I thought that that was a typo but apparently not.

Can anyone explain why this is happening? Or how I can get 480x800 pixels worth of data to show as 480x800?
Or maybe there's some fundamental bit of knowledge I'm completely unaware of :(

Thanks!
Steph

Saurabh_B

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Re: NHD-4.3-480800 HX8369 half pixel writes missing, resolution help
« Reply #1 on: April 11, 2016, 05:27:09 PM »
Hi Steph,

I will be looking into this.

My original Assumption is that the display requires 3 Bytes for 2 pixels in the horizontal direction. This is why were only writing 240 times.

Steph101

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Re: NHD-4.3-480800 HX8369 half pixel writes missing, resolution help
« Reply #2 on: April 11, 2016, 05:42:42 PM »
Hi,

Ok thanks so much!
Yes it seems that that is exactly what's happening, that I have 2x the writes, but I couldn't find a reason why. I thought I made a mistake with the pixel format but I did think it's correct to write 3x for RGB for each pixel, so 24 bits total.
Let me know if you find anything, I'm at a loss :(


Steph101

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Re: NHD-4.3-480800 HX8369 half pixel writes missing, resolution help
« Reply #3 on: April 20, 2016, 05:30:58 PM »
Any luck looking into it?


Saurabh_B

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Re: NHD-4.3-480800 HX8369 half pixel writes missing, resolution help
« Reply #4 on: April 21, 2016, 08:09:58 AM »
Steph,

The code sets up the display to write 1 pixel for every 3 bytes.
For each write sequence we send it 6 bytes. So we send two pixels for each case.

You can modify this by adjusting the Set Pixel Format register. You can find more information about this on page 200 of the controller datasheet.

http://www.newhavendisplay.com/app_notes/HX8369.pdf

Steph101

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Re: NHD-4.3-480800 HX8369 half pixel writes missing, resolution help
« Reply #5 on: April 26, 2016, 01:39:00 PM »
Thanks!!
I think I misunderstood something when reading about 'reads' and using a dummy write in between.
I didn't realize all 6 bytes were read.

Thanks very much!

 

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