6 Replies Latest reply on Nov 18, 2014 2:51 PM by Warren_M

    Adafruit 2.8 inch TFT screen

    Paridhi_Agrawal

      Hi All,

       

      Has anyone worked on the Adafruit TFT screen with Galileo?

       

      Thanks

      --Paridhi

        • 1. Re: Adafruit 2.8 inch TFT screen
          dferyance

          I did some work with that screen a while back https://communities.intel.com/message/224883#224883

          This was with gen 1, and some early firmware.

           

          While I was able to get it working with the adafruit graphics library I really concentrated on having it available on Xorg.

          • 2. Re: Adafruit 2.8 inch TFT screen
            CMata_Intel

            Hi Paridhi_Agrawal;

             

            We are following up on your post to see if you still have any questions you also could check the shields tests report for the Galileo.

             

            Regards

            CMata

            • 3. Re: Adafruit 2.8 inch TFT screen
              KurtE

              Again I have done some work to make it work with the Edison and have versions of code that runs under Arduino IDE as well as code that runs native using compile tools on the board....

               

              I have also have done a little testing on the galileo gen 2, and I know the Arduino version runs (not terribly quick, but...)

               

              More details on the thread: Support for the Adafruit 2.8" TFT display for Arduino Edison

              • 4. Re: Adafruit 2.8 inch TFT screen
                Warren_M

                I have a 2.8" TFT display connected to a Galileo Gen2. I was initially really discouraged, because the performance of the graphicstest sketch was truly miserable.

                 

                I spent the day with this display today, seeing how far I could take graphics performance. Relative to the Intel-tweaked Adafruit_ILI9341 driver, I got between 100-900x speedups, which was heartening. My initial gains were thanks to KurtE's tweaks, mostly reducing the clock divider.

                 

                Additionally, I implemented a buffered version of the Adafruit_ILI9341 class, writing to a dynamically allocated framebuffer, and only presenting the buffer at the end of each test. I'm a software guy, so I was seeking the wins where I could get them. This greatly reduced the number of SPI calls, which makes a difference when you're setting a lot of pixels individually. I copy the framebuffer five rows at a time, nearly maxxing out the 4KB transferBuffer limit. If I could bump that up to 160KB, I could reduce the number of SPI calls by another factor of ~40, which might bring us into the realm of real-time rendering.

                 

                For posterity, here are the timings I got with my tests today (all in microseconds). Note that the Buffered times are utterly dominated by the transferBuffer calls, which take 90% of the frame time.

                 

                IntelKurtEBuffered
                Screen fill     19277465147306771825354
                Text            945530412460079362628
                Lines          90336688125691539 367325
                Horiz/Vert Lines157089561074873 362216
                Rectangles (outline)10014384 1360335382467
                Rectangles (filled) 400070832 10033802 415219
                Circles (filled)   5581994155064526366767
                Circles (outline) 3952260855042394363256
                Triangles (outline)2869661339951955 362937
                Triangles (filled)  12980696625068099375621
                Rounded rects (outline)18880964 17110463362374
                Rounded rects (filled)43462316022428444410756

                 

                The takeaway for me is that Galileo is harshly bandwidth-limited over the SPI interface, but with careful management of calls, you can use this display in applications that don't require real-time responsiveness.

                • 5. Re: Adafruit 2.8 inch TFT screen
                  KurtE

                  Looks great!  It would be great to integrate your stuff in!

                   

                  Kurt

                  • 6. Re: Adafruit 2.8 inch TFT screen
                    Warren_M

                    Source is here: https://github.com/warrenm/Adafruit_ILI9341

                     

                    I don't think it'll merge cleanly with anyone else's fork, but the code is extremely straightforward, if you should care to add buffering capabilities to an existing Adafruit_GFX subclass.

                     

                    Best,

                    Warren