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Thread: RA8876LiteTeensy For Teensy T36 and T40

  1. #1
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    RA8876LiteTeensy For Teensy T36 and T40

    My RA8876 software driver for the BuyDisplay ER-TFTM101-1 10.1 inch tft display w/touch lcd module for use with the T36/T40.
    Found here:
    https://github.com/wwatson4506/Ra8876LiteTeensy

    Touch Screen only tested on the T36 using a slightly modified version of the XPT2046.cpp Teensy driver. Sharing
    SPI ports did not work out well so on the T36 with TallDog's breakout board I was using two SPI ports. One for the
    display and one for the touch screen.
    When a preassembled T40 breakout board (that I don't have to solder) with more than one available SPI port becomes
    available I will test on the T40 and add the XPT2046 files to the repository. To shackey to solder anymore

    WIP, Lot's to do yet functional.

    See README.txt and files in the repository for more information.
    The RA8876 does have the MISO tristate issue as the RA8875 has as well.

    This display is not cheap but works for what I wanted, To be able to see and read the thing
    Gives a lot more real estate than smaller displays, (1024x640) with 16MB of RAM.
    TechToys board uses 32MB of RAM. I think.
    Last edited by wwatson; 12-02-2019 at 01:32 AM.

  2. #2
    I see the 10.1" display has a dot pitch of 0.2175(W)x0.2088(H)mm. Do you have any problem drawing a circle ? Does it look round ?

    I had loads of problems with non square pixels trying to draw circle and boxes.

  3. #3
    Senior Member+ KurtE's Avatar
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    @wwatson - Wondering how much different is this than the RA8875 boards? i.e. wondering if it makes sense to add support for this board into the RA8875 library code that we forked from Sumotoy?

    As you mentioned looks like it has same tri-state issue as their other boards.

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    Quote Originally Posted by skpang View Post
    I see the 10.1" display has a dot pitch of 0.2175(W)x0.2088(H)mm. Do you have any problem drawing a circle ? Does it look round ?

    I had loads of problems with non square pixels trying to draw circle and boxes.
    I haven't found that information yet, but when I draw a rectangle and use a magnifier glass pixels look round. My eyes are not that good.
    There is definitely gaps between the pixels on the horizontal axis which could indicate round pixels. On the vertical axis it is not that pronounced.
    I gave the wrong specs on the resolution of the screen with this driver. It is actually 1024x600 not 1024x640.

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    Quote Originally Posted by skpang View Post
    I see the 10.1" display has a dot pitch of 0.2175(W)x0.2088(H)mm. Do you have any problem drawing a circle ? Does it look round ?

    I had loads of problems with non square pixels trying to draw circle and boxes.
    @Kurte - I was actually thinking the same thing. But the RA8876 controller is quite a bit different than the RA8875 in a lot of ways.
    This is why I think Sumotoy started this GitHub site. https://github.com/sumotoy/RA8876 But sadly at this point has not been able to finish it.
    I want to research the commonality of the two chips as my time allows. One of the main differences are the amount display memory available and the way it is used.
    Trying to find the RA8875 reference manual in all my files
    Maybe you know but I think the display buffer size for the RA8875 is about 768k and the ER-TFTM101-1 has 16M available which with the RA8876 leads to several display page buffers.
    I use this in my RA8876 driver for virtual screens. Some of the basic graphic display engine function are close to the same. User defined characters, rotation, font scaling, mirroring, BTE engine functions and the two PIP windows are different. Maybe through emulation, not sure at this point.
    I would like to see a common driver for both display controllers, but that is probably beyond my skill level
    Sorry @kurte - Replied to the wrong post. Got pulled away again by hungry grand kids.
    Last edited by wwatson; 12-03-2019 at 03:38 AM. Reason: Miss posted:(

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    @skpang - Just did another test with the circle command and used a line thickness of 50. In other words the outer radius was 100 and it repeated the circle 50 times reducing the radius by 1.
    From what I can see with a resolution of 1024X600, the pixels look square. Used white foreground and black background. Obviously with this resolution it left black squares in the solid white circle.
    They are square pixels.

  7. #7
    Quote Originally Posted by wwatson View Post
    @skpang - Just did another test with the circle command and used a line thickness of 50. In other words the outer radius was 100 and it repeated the circle 50 times reducing the radius by 1.
    From what I can see with a resolution of 1024X600, the pixels look square. Used white foreground and black background. Obviously with this resolution it left black squares in the solid white circle.
    They are square pixels.
    I'm not talking about whether the pixel are square or round. I've used some large LCD, when I draw a circle, its not 100% round. It's an oval shape.

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    Quote Originally Posted by skpang View Post
    I'm not talking about whether the pixel are square or round. I've used some large LCD, when I draw a circle, its not 100% round. It's an oval shape.
    It's round.

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    @kurte - I have a couple of questions about the RA8875 display driver from Sumotoy. Has anybody got this working for the T36 and T4?
    If so do you know the links to the latest versions?
    The latest posts about this that I was able to find was this:
    https://forum.pjrc.com/threads/58337...is-it-possible
    But I am not clear if anybody has actually tried it on BuyDisplay's or Adafruit's RA8875 displays.

    Sorry if this redundant. Can't keep up with you guy's

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    Quote Originally Posted by KurtE View Post
    Thanks Kurte and mjs513. Works well with the sketches I have tested on the Adafruit RA8875 board.

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