phkehl / esp32-leddisplay

ESP32 (esp-idf) component for driving dumb LED displays using I2S parallel mode DMA

ESP32 (esp-idf) component for driving HUB75 LED displays using I2S parallel mode DMA

Introduction

This is a leddisplay component for the ESP-IDF [1] for ESP32. It can be used to drive HUB75 LED displays (a.k.a. "Px displays"). It currently works with the following displays: 32x16 1/8 scan, 32x32 1/16 scan, 64x32 1/16 scan, and 64x64 1/32 scan. It currently does not work with 32x16 1/4 scan, 32x32 1/8 scan, 64x32 1/8 scan.

See leddisplay.h for the API.

This code is meant for directly connecting the ESP32 to a display (possibly via a level shifter or buffer). The pinout configuration is available via the sdkconfig ("make menuconfig"). See Kconfig for the defaults.

See leddisplay.c for more information on the code, for references to the origin of the concept and code, and for copyright and license information.

There is an example in the examples directory (leddisplay_test.c).

Happy hacking!

Usage

How to use:

Clone this repository into components/leddisplay of your esp-adf project:

cd /path/to/your/project
git clone https://github.com/phkehl/esp32-leddisplay.git components/leddisplay

Or add it as a git submodule:

cd /path/to/your/project
git submodule add -b master https://github.com/phkehl/esp32-leddisplay.git components/leddisplay

Configuration

Configuration is available in make menuconfig in Component config -> LED Display.

Wiring

The HUB75 (HUB75E) pinout is as follows (male input socket on the back of the display):

                 ______
                /     /|
               +-----+ |
            R1 | o o | |G1
            B1 | o o | |(GND)
            R2 |/o o | |G2
            B2   o o | |(GND) E on HUB75E
             A  /o o | |B
             C | o o | |D
           CLK | o o | |LAT(CH) (STB)
    (BLANK) OE | o o |/ GND
               +-----+

Note that sometimes R1/G1/B1/R2/B2/G2 are labelled R0/G0/B0/R1/B1/G1.

Notes

• The code is relatively slow, in particular the pixel based API (leddisplay_pixel_xy_rgb()), so perhaps increase the CPU clock in sdkconfig (e.g. CONFIG_ESP32_DEFAULT_CPU_FREQ_240=y, CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ=240).

• Tested with esp-idf v3.2.

See also

Original discussion and demo of the concept this code uses in the ESP forum:

• https://esp32.com/viewtopic.php?t=3188

Some generic LED display stuff:

• https://www.sparkfun.com/sparkx/blog/2650

Similar libraries, mostly for the Arduino environment:

• https://github.com/2dom/PxMatrix
  • https://www.instructables.com/id/RGB-LED-Matrix-With-an-ESP8266/
• https://github.com/hzeller/rpi-rgb-led-matrix
• http://docs.pixelmatix.com/SmartMatrix/
  • https://github.com/pixelmatix/SmartMatrix/tree/teensylc
• https://github.com/mrfaptastic/ESP32-RGB64x32MatrixPanel-I2S-DMA

References

• [1] https://github.com/espressif/esp-idf