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Table of Content for arduino:

More pages: May 2019 April 2019 March 2019 January 2019 July 2018 May 2018 April 2018 January 2018 June 2017 April 2017 January 2017 February 2016 January 2015 September 2013 January 2012 December 2011 May 2011 January 2011



2019/04/27 Comparing FastLED::NeoMatrix and SmartMatrix::GFX with PixelMatrix Aurora and Table ME Demos
π 2019-04-27 01:01 in Arduino
Comparing is a misnomer, both libraries pretty much offer the same exact APi (which is the point).
  • https://github.com/marcmerlin/FastLED_NeoMatrix
  • https://github.com/marcmerlin/SmartMatrix_GFX
  • pretty much work exactly the same except for how you init them, but if you use https://github.com/marcmerlin/FastLED_NeoMatrix_SmartMatrix_LEDMatrix_GFX_Demos/blob/master/neomatrix_config.h , you can just include that and your same code will work on both FastLED backed matrices and SmartMatrix backed matrices, even though they are totally different technologies.

    RGBPanels do use less power even when corrected for amount of brightness generated (my estimate is at least 3 times less), they can be a lot more dense, they're cheaper, but they're a pain in the ass to drive since they require constant refreshes at high speed. That being said, as long as you don't exceed 128x64, which is more or less the practical limit on teensy 3.6 and ESP32 due to memory limits due to how SmartMatrix works (a different implementation could push things to at least 128x128 by sacrificing quality for memory use).

    The demos I used for the pictures below are

  • Aurora: https://github.com/marcmerlin/FastLED_NeoMatrix_SmartMatrix_LEDMatrix_GFX_Demos/tree/master/GFX/Aurora
  • Table from Mark Estes: https://github.com/marcmerlin/FastLED_NeoMatrix_SmartMatrix_LEDMatrix_GFX_Demos/tree/master/LEDMatrix/Table_Mark_Estes
  • Here are some shots of Aurora in 32x32 and 32x24 with FastLED::NeoMatrix vs 64x96 with SmartMatrix:





    Video:

    And then shots of Table from Mark Estes in 32x32 and 32x24 with FastLED::NeoMatrix vs 64x96 with SmartMatrix:






    Video:

    2019/04/08 Clubbing, EDM Festival and Burning Man LED Pants and Shirt v4 on ESP32 with RGBPanels and SmartMatrix::GFX
    π 2019-04-08 01:01 in Arduino, Bm, Clubbing
    ===>>> See this full article on the why and evolution of my LED outfit <<<===

    Show me the code:

  • https://github.com/marcmerlin/NeoMatrix-FastLED-IR (same code than my previous shirt, but upgraded for the higher resolution)
  • https://github.com/marcmerlin/SmartMatrix_GFX (API on top of SmartMatrix from Louis Beaudouin, without which this new shirt wouldn't have been possible)
  • https://github.com/marcmerlin/AnimatedGIFs (also original from Louis Beaudouin).
  • https://github.com/marcmerlin/FastLED_NeoMatrix_SmartMatrix_LEDMatrix_GFX_Demos (includes Aurora from Jason Coon, and Table code from Mark Estes)
  • Related pages:

  • Shirt V2
  • Shirt V3
  • SmartMatrix GFX I had to write (including Teensy with SmartMatrix v4 shield vs ESP32)
  • Using FatFS on ESP32 to store Animated GIFs
  • Diffusers for RGBPanel
  • Details: After version 3 of my shirt with a neopixel matrix, I had good fun, but was hoping to do more. Its resolution was only 24 x 32 pixels, enough to display fun patterns, but it's really not a lot of pixels.


    After months and months of work, here is version 4:


    Video demo:

    Sadly, going up in resolution with addressable pixels, is not that easy. While in theory you should be able to fit at least 2 addressable pixels per centimeter (aka P5). Currently my premade panels are P10, which is the only thing I could buy pre-made.

    What allowed me to switch were those flexible P4 RGB Panels from Azerone: https://amazon.com/gp/product/B07F87CM6Y


    With their P4 resolution, I'm able to fit 96x64 on my body using 3 panels of 64x32 chained together. The 3rd panel is then chained to the 2nd set of 3 panels in my back:


    On the old shirt, I put the rear panel inside the shirt, using the shirt as a diffuser, but with the RBGPanels, they were too thick for this to be practical, so I had to put them on top of the shirt. As a result, I ended up uing a black shirt which matches the color of the panels. I had to attach velcro to the new shirt, and confirmed that supergluing them was so much faster than sawing, and worked just as well:


    I unsoldered the power connectors that were too thick, and used small metal wire to connect the panels together (see top middle of the picture). Turned out those metal wires were a mistake as they can cause shorts on the LEDs on the other side of the board:


    Another thing I learned was that the holes I was using to put a metal wire to carry the panels over my shoulders, can't actually take the load, and the wire can cause damage to the copper trace that is just next to the hole. As a result, I replaced the metal wires with fishing wire and didn't use the bigger holes for load bearing:


    Speaking of removing thickness from the board, I removed the top of the ribbon connectors to make them a bit thinner. Sadly, RGBPanels still require 15 wires to send the video signal:


    I then took one panel and covered it with defusing foam (the rear panel, so that it's not too sharp and blinding to people behind me), while the front panel only has the plastic cover to protect the panels and offer a bit of extra diffusion:




    you can see the difference between the diffusion levels
    you can see the difference between the diffusion levels

    I then protected the rear of the panels given how much electronics were exposed:


    Small details had to be solved, like making sure I had enough amps going through the wires (use thicker wires). Without that, my brightest pattern that uses 8 amps, didn't quite make it:


    For fun, I made a pattern that scrolls my C++ scrolling code on the screens:


    As for the CPU that runs it, I picked the ESP32 since it's dual core and can do refreshes on one core while running code on the other core. My SmartMatrix::GFX page has more details on using ESP32 with SmartMatrix


    I went from a breadboard prototype to Jason Coon's ESP32 level shifter board, much more tidy
    I went from a breadboard prototype to Jason Coon's ESP32 level shifter board, much more tidy

    This video shows how things are wired from the ESP32 to the panels:

    Here is what the whole power system looks like:

  • 2 4S Lipos, 5Ah, 80wh, giving a total 160Wh of energy
  • Amp meter in line with the lipos and cell tester with low voltage warning buzzer
  • On off/switch
  • Amp gauge with timer to know how much energy flowed from the batteries (you can't run lipos down or they'll die)
  • Tobsun DC-DC converter to take voltage down to 5V
  • 2nd voltage regulator to bring the voltage further down to 3.3V for the El Wire glasses
  • 5V goes to RGBPanels via separate thick wire to carry the amps
  • ESP32 with level shifters from 3.3V back up to 5V for the RGBPanels (6 channels for the colors to level shifters, 4 address lines to do 16 scan line refreshes). CPU runs SmartMatrix::GFX and NeoMatrix-FastLED-IR
  • 16th data line is used for the Neopixel strips on my arms and legs, running the same code than the previous shirt
  • Walk through video:

    I have around 60 demos running on the panels, including some Animated Gifs on ESP32 FFat with the library I was able to improve:





    Here is an example of 3 levels of diffusers, including a raw set of panels with no diffusers:










    After going to Luminosity Beach Festival, a underpaid and undertrained security guard at the entrance freaked out at the wires, so I made boxes to hide the wires and hopefully remove the "OMG, it's a bomb" reflex that some people might have:

    2 batteries, fuse, meters and output
    2 batteries, fuse, meters and output

    adapter box that takes 16V down to 5V and measures current used while distributing power
    adapter box that takes 16V down to 5V and measures current used while distributing power

    both boxes together are bigger than my previous setup, but looks a bit better
    both boxes together are bigger than my previous setup, but looks a bit better

    You can see a demo of the outfit being worn:

    If you don't have time for all this, and are ok with 64x64, you can try this backpack from gearbest with everything built in and a very thin board. Just not fun for me because I can't run my own code on it:



    2019/04/01 SmartMatrix, SmartMatrix Shield v4 for Teensy, ESP32 shield with level shifter, and SmartMatrix::GFX
    π 2019-04-01 01:01 in Arduino

    Less blah-blah, more code

    Sure, there you go: https://github.com/marcmerlin/SmartMatrix_GFX

    What is it?

    https://github.com/marcmerlin/SmartMatrix_GFX is a zero copy, zero extra buffer frontend to Smartmatrix, which is the best arduino API driver for RGB Panels.
    It supports these 4 APIs seemlessly and concurrently in the same code:
  • Adafruit::GFX https://github.com/adafruit/Adafruit-GFX-Library
  • FastLED https://github.com/FastLED/FastLED
  • LEDMatrix https://github.com/Jorgen-VikingGod/LEDMatrix
  • SmartMatrix https://github.com/pixelmatix/SmartMatrix
  • Give me Examples

    Sure: https://github.com/marcmerlin/FastLED_NeoMatrix_SmartMatrix_LEDMatrix_GFX_Demos

    This page that shows how I built my EDM Festival and Burning Man LED Pants and Shirt v4 on ESP32 with RGBPanels and SmartMatrix::GFX using this library.

    More blah-blah & rationale for SmartMatrix::GFX

    Last year, I wrote FastLED::NeoMatrix to let me run Neopixel Matrices made out of pre-made panels arranged as a bigger panel. This was the end result: http://marc.merlins.org/perso/arduino/post_2018-04-23_FastLED_NeoMatrix-library_-how-to-do-Matrices-with-FastLED-and-Adafruit_GFX.html

    This allowed me to do my Party shirt v3 based on a NeoPixel Matrix

    However, the main problem I had was the limited pixel density of those neopixels and the price per pixel given that each pixel has a very small computer chip attached. My shirt was only 768 pixels per side (32x8x3) which cost $80 per side. While my shirt looked cool (i.e. better than nothing), 32x24 resolution isn't that much to display cool stuff. I made the best of it, but I knew that I wanted more pixels.
    While it's technically possible to get 0.5cm pitch (i.e. P5) with nepixels, there is no such panel I could buy today and I wasn't really interested in fabbing my own, so I switched to RGBPanels.

    What allowed me to switch were those flexible P4 RGB Panels from Azerone: https://amazon.com/gp/product/B07F87CM6Y


    RGBPanels are a totally different technology based on row scan technology, pretty much like the 8x8 matrices I wrote a scanning driver for but with a built in shift register to load up all the column for each color, multiplied by 2 as for historical reasons you can update 2 halves of the panel separately.
    With 32x64 panels, or even 64x64 panels, that's a lot of pixels to push serially via shift registers and address lines to select the line you've currently pushed all those columns for. The LEDs need to be refreshed very quickly to avoid visible flickering.
    This limits the list of reasonble CPUs for higher resolutions to teensy 3.6 and ESP32, which also removes the multiple slower and/of inefficient drivers out there. Options I looked at and weren't suitable:

  • https://github.com/adafruit/RGB-matrix-Panel/ (the adafruit driver is actually efficient, and recently got ESP32 support, but does not support panel chaining past very basic chaining)
  • https://github.com/mrfaptastic/ESP32-RGB64x32MatrixPanel-I2S-DMA/ (not well tested for larger chained panels, but efficient with DMA and offers Adafruit::GFX API. It also supports page level refresh instead of line level, so flickering is more manageable on it)
  • https://github.com/2dom/PxMatrix ( supports ES8266, but is 6 times slower than normal drivers by shifting all 6 colors onto a single wire ( https://community.pixelmatix.com/t/has-anyone-used-https-github-com-2dom-pxmatrix/384 ) ).
  • https://github.com/NeoCat/ESP32-P3RGB64x32MatrixPanel is an alternate driver with DMA support and apparently unsupported. I have no idea why this driver even exists when
  • This leaves us with the most complete driver of them all, Smartmatrix. The main pluses are:

  • Great support from the author on https://community.pixelmatix.com
  • Best support for chaining panels (up to 128x128 on teensy, and maybe 64x128 on ESP32 before it runs out of DMA RAM)
  • High color depth 24bpp or higher (which honestly is more than I need, 24bpp is more than most panels can probably reasonably show and 16bpp would likely be enough for my use). I still wouldn't mind if SmartMatrix offered 16bpp in exchange for a higher refresh rate or lower resource and memory utilization (also allowing for a higher resolution on a given CPU)
  • Support for the 2 fastest common arduino like microcontrollers: teensy 3.6 and ESP32 (teensy 3.1/3.2 is not fast enough to refresh 64x64 well enough, and teensy 3.5 is slower than 3.6, so no reason to buy one)
  • Very powerful API with multiple layer support (great if you can use it, although I'll admit that I only need drawpixel thanks to Adafruit::GFX)
  • So, SmartMatrix is great, but I have all this code that relies on one or more of those APIs:

  • Adafruit::GFX https://github.com/adafruit/Adafruit-GFX-Library
  • FastLED https://github.com/FastLED/FastLED
  • LEDMatrix https://github.com/Jorgen-VikingGod/LEDMatrix
  • I have a reasonble collection of demos I've gathered (a few I wrote myself), here: https://github.com/marcmerlin/FastLED_NeoMatrix_SmartMatrix_LEDMatrix_GFX_Demos and they use a combination of those 3 APIs.
    The goal was for me to be able to re-use that code and make it work on both FastLED backends and SmartMatrix backends, which why I wrote SmartMatrix::GFX
    https://github.com/marcmerlin/SmartMatrix_GFX offers a GFX compat layer that is virtually identical to my FastLED::NeoMatrix library and allows you to run the same code onto of either FastLED or SmartMatrix supported panels.

    Hardware, Teensy 3.6 and SmartMatrix Shield v4

    The easiest way to use SmartMatrix is to use the SmartMatrix Shield v4 from Louis Beaudoin.
    If you are going to drive 64x64 and above, skip the teensy 3.0/3.1/3.2 and go directly to teensy 3.6. It costs more, but you'll want the extra CPU speed (teensy 3.1 can barely run 64x64 with an ok-ish refresh if you overclock it, if you must use the older chip).

    Here is what the SmartMatrix shield looks like with a small patch I made to take USB power and send it to the panel (my laptop can output 2A over USB). Note that this is not safe with teensy v3.1/3.2 as it's not meant to pass that much current from its USB connection, but teensy 3.6 can do it fine as its fuse is located after the V+ connection on the chip:

    Originally I used the APA connector to send power to the panel
    Originally I used the APA connector to send power to the panel

    2x 32x64 chained P4 panels with a sad cable extension I had to make, vs pre-made 64x64 P3 panel
    2x 32x64 chained P4 panels with a sad cable extension I had to make, vs pre-made 64x64 P3 panel

    SmartMatrix basic demo
    SmartMatrix basic demo

    The main problem with RGBPanels is that if the refresh rate isn't fast enough, they look bad on pictures. This is the main reason I switched to ESP32 which is dual core and can push a higher refresh rate via DMA than teensy can:


    Chained panels giving mirrored output on a total display of 128x96:


    Hardware: ESP32

    As mentioned above, ESP32 is dual core, so it can update the panel on one core using DMA, while the other core can run your code. It is more efficient, however, it runs out of DMA memory around 64x128 resolution (I run 64x96 myself and had to optimize code to make things fit)..

    Here are shots of what it looks like with Jason's shield:

    it's reasonably compact, 15 IO's for SmartMatrix (14 are really required), IR connected to port 34, and IO 16 connected to a NeoPixel strip
    it's reasonably compact, 15 IO's for SmartMatrix (14 are really required), IR connected to port 34, and IO 16 connected to a NeoPixel strip

    This shows my flexible P4 96x64 panels I bought on amazon from Azerone, 3 tied together, one shown upside down for scale, a blank shield from Jason Coon, how I cut a 16 pin IDC ribbon cable and made it an in line row of pins I can connect into Jason's shield after having added a riser, and a patched board with IR connector on the back, and a yellow wire to redirect the pin Jason's board connected to RX which I use for debugging, to unused pin 27 instead:


    While Jason's board is not perfect for this use, it's much better than my self made protoboard full of wires to connect the 74hc245 level shifters:


    Here's a quick video summary that shoes the wiring and layout:

    Tips for ESP32 and memory:

  • Do not use arrays, ESP32 does badly with array allocation for complicated reasons and bugs ( https://github.com/espressif/arduino-esp32/issues/2567 )
  • See also https://community.pixelmatix.com/t/esp32-runs-out-of-some-ram-when-using-64x96/394 for more background
  • And how SmartMatrix will crash if it can't allocate enough DMA RAM at startup (again, switch your code to use malloc and allocate after you've ran SmartMatrix init): https://community.pixelmatix.com/t/cant-get-enough-dma-memory-on-esp32-assertion-matrixupdateframes-1-null/406/19
  • SmartMatrix.begin(xxx) lets you force SmartMatrix to use less RAM and use more lsbMsbTransitionBit which makes display worse but can help
  • More details on what memory is available on ESP32: https://github.com/espressif/esp-idf/issues/1934#issuecomment-389087100
  • Another ESP32 corner case bug I found if you use global static arrays: https://github.com/espressif/esp-idf/issues/3211
  • Do not even think about using local arrays in functions, that's worse as they go on the stack and will smash the stack (I think you're limited to around 8KB)
  • ESP32 has SPIFFS to use its flash to store data like Animated GIFs. You will find it unacceptably slow if you store 1MB or more and seek across a bunch of files, Instead, use FatFS as explained here:

  • http://marc.merlins.org/perso/arduino/post_2019-03-30_Using-FatFS-FFat-on-ESP32-Flash-With-Arduino.html
  • https://github.com/marcmerlin/esp32_fatfsimage
  • Make sure you use FFat.begin(0, "", 1) to save RAM
  • SmartMatrix Support:
    Louis Beaudoin added ESP32 support in this branch https://github.com/pixelmatix/SmartMatrix/tree/teensylc .
    You'll want to look at this file for how to wire your ESP32: https://github.com/pixelmatix/SmartMatrix/blob/teensylc/src/MatrixHardware_ESP32_V0.h#L62
    While you can apparently get away with no using a level shifter (at least with some panels), I chose to use one. First, I did it the hard way with a protoboard and level shifter chips, and then I switched to Jason Coon's 16 output ESP32 shield.
    I then used a HUB75 ribbon, cut the end, and made a straight connector that went directly into the IO pins coming fromthat shield

    Here are pictures of what it looks like:

    Hopefully in the near future, one will be able to buy a pre-made ESP32 SmartMatrix shield.

    End result

    Here are some demos of https://github.com/marcmerlin/FastLED_NeoMatrix_SmartMatrix_LEDMatrix_GFX_Demos and https://github.com/marcmerlin/NeoMatrix-FastLED-IR on top of SmartMatrix with 2 chained subpanels of 64x96 (each made out of 3 64x32 panels):













    As a side note, RGBPanels look better when you have a diffuser sheet in front, so here is a page on that.


    More pages: May 2019 April 2019 March 2019 January 2019 July 2018 May 2018 April 2018 January 2018 June 2017 April 2017 January 2017 February 2016 January 2015 September 2013 January 2012 December 2011 May 2011 January 2011