The Fewest ESP8266 IO Pins to Drive a Large RGB Matrix?
Channel: bornach
Date: 2019-05-06

RGB LED matrix displays intended for use in video walls are controlled using a dozen or so data and control input pins. Microcontrollers such as the ESP8266, these GPIO pins are in short supply. A popular method by which an ESP8266 can drive such a display is by using the PxMatrix library which required nearly every IO pin to be used to drive the matrix inputs. This includes the I2C pins (D1, D2) and the D4 data pin often used for 1-Wire protocol by Wemos shields. Currently it is not possible for an ESP8266 to drive a video wall matrix and use Wemos sensor shields at the same time.

However by using a few 74xx ICs the number GPIO pins needed to drive the RGB matrix can be reduced to as little as 3. This potentially will allow an ESP8266 to drive a large RGB panel and still have the pins left free which can be used with many of the Wemos shields.


Adafruit matrix library
https://github.com/adafruit/RGB-matrix-Panel/blob/master/RGBmatrixPanel.cpp

Ray's Logic website on RGB matrix panels
www.rayslogic.com/propeller/Programming/AdafruitRGB/AdafruitRGB.htm

PxMatrix library
https://github.com/2dom/PxMatrix

Brian Lough - hooking up an RGB Matrix
https://www.youtube.com/watch?v=YvU_ZfF7vs4

Brian Lough's D1 Mini Matrix Shield on Tindie
https://www.tindie.com/products/brianlough/d1-mini-matrix-shield/

Kris Cochrane - soldering the RGB matrix
https://www.youtube.com/watch?v=5A3BWB7k_YI

Andreas Spiess - Wemos shields and pin assignements
https://www.youtube.com/watch?v=G73fiaOpUAc

Wemos shields and they pins they use
https://wiki.wemos.cc/products:d1_mini_shields