* This is an ESP32 Arduino/IDF library for HUB75 / HUB75E RGB LED panels.
* This library 'out of the box' (mostly) supports HUB75 panels where TWO rows/lines are updated in parallel... referred to as 'two scan' panels within this library's documentation.
* 'Four scan' panels are also supported - but please refer to the Four Scan Panel example.
* The library uses the DMA functionality provided by the ESP32's 'LCD Mode' for faster output.
-**Low CPU overhead** - Pixel data is sent directly with the use of hardware-backed DMA, no CPU involvement
-**Fast** - Updating pixel data involves only bit-wise logic over DMA buffer memory, no pins manipulation or blocking IO
-**Full screen BCM** - Library utilizes [binary-code modulation](http://www.batsocks.co.uk/readme/art_bcm_5.htm) to render pixel color depth / brightness over the entire matrix to give reasonable colour depth
-**Variable color depth** - Up to TrueColor 24 bits output is possible depending on matrix size/refresh rate required
-**CIE 1931** luminance [correction](https://ledshield.wordpress.com/2012/11/13/led-brightness-to-your-eye-gamma-correction-no/) (aka natural LED dimming) implemented
-**Adafruit GFX API** - Library can be built with AdafruitGFX, simplified GFX or without a GFX API at all
## ESP32 variants supported
* Original ESP32 - That being the ESP-WROOM-32 module with ESP32‑D0WDQ6 chip from ~2017.
Please use the ['Memory Calculator'](/doc/memcalc.md) to see what is *typically* achievable with the typical ESP32. 
For the ESP32-S3 only, you can use SPIRAM/PSRAM to drive the HUB75 DMA buffer when using an ESP32-S3 with **OCTAL SPI-RAM (PSTRAM)** (i.e. ESP32 S3 N8R8 variant). However, due to bandwidth limitations, the maximum output frequency is limited to approx. 13Mhz, which will limit the real-world number of panels that can be chained without flicker. Please do not use PSRAM as the DMA buffer if using QUAD SPI (Q-SPI), as it's too slow.
For all other ESP32 variants (like the most popular ‘original’ ESP32), [only *internal* SRAM can be used](https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-I2S-DMA/issues/55), so you will be limited to the ~200KB or so of 'free' SRAM (because of the memory used for your sketch amongst other things) regardless of how many megabytes of SPIRAM/PSRAM you may have connected.
* 'Two scan' panels where **two** rows/lines are updated in parallel.
* 64x32 (width x height) 'Indoor' panels, such as this [typical RGB panel available for purchase](https://www.aliexpress.com/item/256-128mm-64-32-pixels-1-16-Scan-Indoor-3in1-SMD2121-RGB-full-color-P4-led/32810362851.html). Often also referred to as 1/16 'scan panel' as every 16th row is updated in parallel (hence why I refer to it as 'two scan')
* 64x64 pixel 1/32 Scan LED Matrix 'Indoor' Panel
* 'Four scan' panels where **four** rows/lines are updated in parallel.
* 32x16 pixel 1/4 Scan LED Matrix 'Indoor' Panel using an ingenious workaround as demonstrated in the Four_Scan_Panel example.
Due to the high-speed optimized nature of this library, only specific panels are supported. Please do not raise issues with respect to panels not supported on the list below.
* FM6126A AKA ICN2038S, [FM6124](https://datasheet4u.com/datasheet-pdf/FINEMADELECTRONICS/FM6124/pdf.php?id=1309677) (Refer to [PatternPlasma](/examples/2_PatternPlasma) example on how to use.)
* ICN2053 / FM6353 based panels - Refer to [this library](https://github.com/LAutour/ESP32-HUB75-MatrixPanel-DMA-ICN2053), which is a fork of this library ( [discussion link](https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA/discussions/324)).
Library also tested to work fine with PlatformIO, install into your PlatformIO projects' lib/ folder as appropriate. Or just add it into [platformio.ini](/doc/BuildOptions.md) [lib_deps](https://docs.platformio.org/en/latest/projectconf/section_env_library.html#lib-deps) section.
Refer to the '*default-pins.hpp' file within the [applicable platforms folder](https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA/tree/master/src/platforms).
If you want to change the GPIO mapping at runtime, simply provide the wanted pin mapping as part of the class initialization structure. For example, in your sketch have something like the following:
Make sure you also connect one of the HUB75 interfaces ground pins to a ground pin of the ESP32, otherwise you may get electrical artefacts on LED Matrix Panel.
### Can I use with a larger panel (i.e. 64x64px square panel)?
If you want to use with a 64x64 pixel panel (typically a HUB75*E* panel) you MUST configure a valid *E_PIN* to your ESP32 and connect it to the E pin of the HUB75 panel! Hence the 'E' in 'HUB75E'
Below is a bare minimum sketch to draw a single white dot in the top left. You must call begin() before you call ANY pixel-drawing (fonts, lines, colours etc.) function of the MatrixPanel_I2S_DMA class.
Once this is working, refer to the [PIO Test Patterns](/examples/PIO_TestPatterns) example. This sketch draws simple colors/lines/gradients over the entire matrix and it could help to troubleshoot various issues with ghosting, flickering, etc...
For example: If you want to chain two of these horizontally to make a 128x32 panel you can do so by connecting the panels in series using the HUB75 ribbon cable. Than you must provide proper configuration structure to the class constructor letting it know that you use "one long virtual matrix chain". Refer to [Pattern Plasma](/examples/2_PatternPlasma/) example for all the details about configuration setup.
Finally, if you wanted to chain 4 x (64x32px) panels to make 128x64px display (essentially a 2x2 grid of 64x32 LED Matrix modules), a little more magic will be required. Refer to the [Chained Panels](examples/ChainedPanels/) example.
Resolutions beyond 128x64 are more likely to result in crashes due to [memory](/doc/i2s_memcalc.md) constraints etc. You are on your own after this point - PLEASE do not raise issues about this, the library can't magically defeat the SRAM memory constraints of the ESP32.
By default you should not need to change / set the brightness value (which is 128 or 50%) as it should be sufficient for most purposes. Brightness can be changed by calling `setPanelBrightness(xx)` or `setBrightness8(xx)`.
Although Arduino IDE does not [seem](https://github.com/arduino/Arduino/issues/421) to offer any way of specifying compile-time options for external libs there are other IDE's (like [PlatformIO](https://platformio.org/)/[Eclipse](https://www.eclipse.org/ide/)) that could use that. Check [Build Options](doc/BuildOptions.md) document for reference.
If you are facing issues with image ghosting when pixels has clones with horizontal offset, than you try to change Latch blanking value. Latch blanking controls for how many clock pulses matrix output is disabled via EO signal before/after toggling LAT signal. It hides row bits transitioning and different panels may require longer times for proper operation. Default value is 1 clock before/after LAT row transition. This could be controlled with `MatrixPanel_I2S_DMA::setLatBlanking(uint8_t v)`. v could be between 1 to 4, default is 1, larger values won't give any benefit other than reducing brightness.
Having a good power supply is CRITICAL, and it is highly recommended, for chains of LED Panels to have a 1000-2000uf capacitor soldered to the back of each LED Panel across the [GND and VCC pins](https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-I2S-DMA/issues/39#issuecomment-720780463), otherwise you WILL run into issues with 'flashy' graphics whereby a large amount of LEDs are turned on and off in succession (due to current/power draw peaks and troughs).
- Refer to this guide written for the [rpi-rgb-led-matrix library](https://github.com/hzeller/rpi-rgb-led-matrix/blob/master/wiring.md#a-word-about-power) for an explanation.
- Refer to this [example](https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-I2S-DMA/issues/39#issuecomment-722691127) issue of what can go wrong with a poor power supply.
- Refer to [this comment](https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-I2S-DMA/issues/35#issuecomment-726419862) in regards to certain panels not playing nice with voltages, and a 3.3volt signal that the ESP32 GPIO can only provide.
* [Galaxy Man](https://github.com/Galaxy-Man) for donation of 1/16 scan panels to support the implemenation of led matrix panel chaining (virtual display) support
* [Pipimaxi](https://github.com/Pipimaxi) for the donation of a ESP32-S2 and [Radu](https://github.com/juniorradu) for the donation of an ESP32-S3 to enable support for ESP32 S2/S3's to be tested and implemented.
* [Mark Donners](https://github.com/donnersm) ('The Electronic Engineer' on [youtube](https://www.youtube.com/watch?v=bQ7c9Vlhyp0&t=118s)) for the donation of a 1/8 scan panel to build and test working support of these led matrix panels!
If you want to donate money to the project, please refer to [this discussion](https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA/discussions/349) about it. If you want to donate/buy an LED panel for the library author to improve compatibility and/or testing - please feel free to post in the same [discussion](https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA/discussions/349).
