LED Matrix Dsply


LED Matrix Programming8x8-LED-Matrix LedControl.cpp Custom-Seven-Segment-LED
Led7Seg Sketch LedControl LedCscd MAX72xx
MAX7219 LedCtrlLib LedCtrlSftw LedDemos
LedMtrx LedCtrlHdw 8x8 LED generator Real 8x8 LED Gen
LedControl Info Max7219 Clock Max7219 Clock MD_MAX72xx.cpp
MD_MAX72xx.ESP32 LedMtx & ESP32 Matrix Characters

In-Page links
NTP LED Matrix RTC ESP01

The MAX72xx uses an SPI interface, and it's Vcc is 5V. On SPI interface, the MAX72xx only uses MOSI as it's data pin.

I want an NTP controlled clock for numerous projects.   Yes, I do need another clock in our Den and bedroom (with a projector), but I also need a thermostat for the mini-split AC in the shop and our irrigation controller.   So I got busy.  

MAX7219 Vcc: 3.3 - 5V

  1. First was to be able to get the NTP packets from our NTP server and extract the time information in a format compatable with an RTC card.
  2. be able to pull the time/date etc. from the RTC
  3. display it on a display large enough for Betty and I to see (we're both seniors).  

NTP Packets

I originally started out using an Arduino Nano and an ESP01 adapter with an esp8266, but found I had consumed too much ram.   So I switched to an ESP32 and was pleased with result (so far).

RTC

The RTC (Real Time Clock) is a DS3231 which appears to be well supported.  

LED Matrix

A most of the LCD displays were either too small or too expensive, when I came upon the 32x8 LED Matrix displays.      

Bottom of a MAX7219.  
There are at least 3 types:
Red: 1088AS ?
Blu: 1088AB 46
Grn: 1088AYG  

SigNanoESP32NodeMCU
Vin5V5V
GndGndGnd
DinD11 (MOSI)23 (vspi MOSI)
ClkD13 (SCK)18 (vspi SCK)
CsD7D7