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Author Topic: Non square pixel support BT817/818 using HSF  (Read 9299 times)

Turby

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Non square pixel support BT817/818 using HSF
« on: April 06, 2021, 10:49:26 AM »
Hi,

I'm looking to purchase a 7" display with the new Eve4 BT817 controller. I am migrating an existing application which uses a 5" display which has square pixels. From reading 7" TFT datasheets I see that pretty much all of them have non-square pixels. For example the 7" 1024x600 Riverdi RVT70HSBFWN00 has a pixel size of 0.1506 (width) × 0.1432 (height).

The main reason why I want this is to display round circles, not ellipses, it also makes any math for coordinates easier.

I've searched the various datasheets but not finding much in the way of how to use Horizontal Scanout Filter. Even how its actually set (see https://brtchip.com/wp-content/uploads/Support/Documentation/Datasheets/ICs/EVE/DS_BT817_8.pdf)

If I were to keep 1024 x 600 and set HSF to get square pixels, would I then see an unused region on the right hand edge of the display? If so, could I then increase the resolution to (for example) 1060 x 600 to use the entire width of the display?

Is there an example of this being used I could look at?

As an aside does the Eve Screen Builder / Design software (or any other similar tools) take HSF into consideration?

Many thanks
Toby
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BRT Community

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Re: Non square pixel support BT817/818 using HSF
« Reply #1 on: April 07, 2021, 04:21:43 PM »
Hello,

Thank you for your question.

The Horizontal Scanout Filter is controlled on the BT817 with the CMD_HSF command.

Please see section 5.111 of the BT81X Programmers guide for an example:
https://brtchip.com/wp-content/uploads/Support/Documentation/Programming_Guides/ICs/EVE/BRT_AN_033_BT81X_Series_Programming_Guide.pdf

Quote from: Turby on April 06, 2021, 10:49:26 AM
If I were to keep 1024 x 600 and set HSF to get square pixels, would I then see an unused region on the right hand edge of the display? If so, could I then increase the resolution to (for example) 1060 x 600 to use the entire width of the display?

Yes that is correct, you must alter the HSIZE display setting to take into account the implementation of HSF.

Unfortunately neither EVE Screen Designer or EVE screen Editor have implemented support for CMD_HSF as of yet.

Best Regards,
BRT Community
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