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• Blinky

  Ellie Hussey • 11/08/2020 at 01:30 • 0 comments

  It might not look like much, but I got everything installed and set up and figured out enough to get this development board up and running 😁
  Today, we blink some lights. Tomorrow, we blink the world! or something

  
  

  Here's an example of the glitchy 10FPS via SPI I could get with the ESP32 and with an STM32F4XX.  The intent was to draw a black bar across the screen and change its location by 1 pixel per frame.  It's sending the entire 240 lines each frame, so this should accurately represent the capabilities regardless of what image is displayed.

  and similar code running on an STM32F746 clocked to 180MHz (though SPI was still <5MHz).  The difference between a glitchy 10FPS and a smooth 40/60FPS is everything:

• Processor possibilities...

  Ellie Hussey • 10/31/2020 at 23:16 • 0 comments

  A friend let me know about an alternative to the ST series - an ARM Cortex M33 system by Renesas

  It looks ideal going by the specs (and that is one sweet eval board), so I'm going to work on getting their dev environment set up and my current code working on it.  A lot will depend on BOM impact - this is actually supposed to be cheaper - so if it proves as workable as I hope, this could reduce the expected cost while giving better performance and better power savings.

  The ESP32 I initially planned to use simply wasn't able to drive the LCD fast enough.  The SPI speeds are compatible, but blitting a 400x240 buffer at anything more than 8-10FPS resulted in a ton of glitches and artifacts.  On top of that, the amount of I/O to deal with (I was originally including two separate GPIO expanders / key matrix controller chips just to handle it all) was just not ideal.  Switching to an ST or Renesas option gives me the option of 100 or 144-pin TQFP packaging with enough GPIO to handle everything and then some.  As a bonus, comms becomes separate from the core processor which can only aid security.

• Progress to date

  Ellie Hussey • 10/31/2020 at 23:06 • 0 comments

  I'm a couple months into this already, so I've already tried and discarded a dozen ideas.  Right now, I have an STM32F746 dev board driving the Sharp LCD at speeds up to 60FPS (finally), though I'm dropping that to 30-40FPS for practical usage.  I'm making some progress getting a basic FreeRTOS structure set up (using CMSIS).

  I've gotten some individual module boards fabbed for basic 3.3V LDO supply and 5V boost for the LCD, and tested out a couple of strategies for connecting the LCD via a 0.5mm FIPS socket
  

  I'm dusting off and updating the layout for handling a blackberry trackball properly (more difficult than you'd think with a two-layer board, if you want to fit in LEDs)

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