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Thread: Ssd1963 vs ra8875 with teensy 3. 6

  1. #1

    Ssd1963 vs ra8875 with teensy 3. 6

    I am planning to make a system that uses a 5" lcd screen that runs on a teensy 3.6.
    After looking around it seems those two drivers are the common option. None seem to be perfectly supported by a library on the 3.6 (?). I ha e seen various modules and they all seem to boil down to the same specifics.
    I will be drawing a rather basic text based UI, use simple background color changes as visual feedback (think menu navigation) and maybe use touch screen and graphic 'bars' for the user to edit specific settings. Refresh rate is not crucial since I won't have any video. The whole thing should be as light as possible on the MCU since I will be running a real time application where delay is important (MIDI).
    1. Since i plan to stay at 3.3V for the whole system i assume I don't need any specific arduino shield, correct?
    2. Which of the two controllers is easier to get up and running in terms of code on the teensy? I want to avoid delving into libraries and having to tweak stuff.
    3. What about touch screen? Does it readily work?
    4. should i add anything extra to my system like memory etc? Would it even make sense to use a dedicated mcu for the display duties (ditch the 3.6 and maybe roll with two LC or something)
    5. SSD1963 uses a parallel data interface. Would I run into tons of issues if I used a serial to parallel converter and save some pins?
    I have tried to confine the application to 3.5" but it is really hard, i could really use the 5" upgrade.
    I'm competent with arduino/teensy programming and have good hardware skills (ece specialising in electronics hardware). Graphics programming is a first for me I would appreciate any help.

  2. #2
    Senior Member PaulStoffregen's Avatar
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    I haven't used SSD1963.

    RA8875 works pretty well with Adafruit's library. It has excellent performance for its built-in fonts, and drawing shapes like rectangles. For copying bitmaps, the RA8875 acceleration doesn't help at all.

    RA8875 does not play nice with other SPI chips, because it does not tri-state its MISO pin. It's 2nd issue is described here.

    https://www.pjrc.com/better-spi-bus-design-in-3-steps/

    If you will connect any other SPI chip to the same MISO pin, you'll need to add a tri-state buffer to keep RA8875 from interfering when you try to read the memory of that other chip.

  3. #3
    I have read about those issues I think I can handle them. The system will sit ona pcb that contains the teensy and any extra interfacing ICs.
    I read that the performance of that library is pretty slow compared to what you can achieve with ra8875. I'd rather have a solution that is optimised at least on a basic level.
    Above all though I need a solution that will be fast to figure out and program. I have little knowledge on grafic programming to be able to judge for myself which chip would be better...

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