Esp32 + max7219

[brad3260]

Hello everyone, I have been banging my head against the wall all day trying to figure this out and I'm at a lost. I have an ESP32 wired to a MAX7219 dot matrix with the following code. It's just a clock, I've made one of these by hard coding my wifi creds and it works with no problem. Now I'm trying to make another using wifi manager. The following code works perfectly after compiling but when I unplug the ESP32 from my computer and plug it back into the same port, or into a wall outlet, nothing gets displayed on the dot matrix. I can see that it is going out and receiving the time via the serial monitor. Anyone have any ideas? Any help would be much appreciated!!

#include <WiFi.h>
#include "time.h"
#include <MD_Parola.h>
#include <MD_MAX72xx.h>
#include <SPI.h>
#include <WiFiManager.h> // https://github.com/tzapu/WiFiManager

// select which pin will trigger the configuration portal when set to LOW
#define TRIGGER_PIN 19
int timeout = 120;

#define HARDWARE_TYPE MD_MAX72XX::FC16_HW
//#define HARDWARE_TYPE MD_MAX72XX::GENERIC_H

#define MAX_DEVICES 4
#define CLK_PIN   18 
#define DATA_PIN  23 
#define CS_PIN    5 
MD_Parola Display = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);

const char* ntpServer = "pool.ntp.org";
const long  gmtOffset_sec = -18000;
String minute ="";
int thr;
String hr = "";
const int   daylightOffset_sec = 3600;

void printLocalTime()
{
  struct tm timeinfo;
  if(!getLocalTime(&timeinfo)){
    Serial.println("Failed to obtain time");
    return;
  }
  Serial.println(&timeinfo, "%A, %B %d %Y %H:%M:%S");
  Display.setTextAlignment(PA_CENTER);
  if(timeinfo.tm_min<10) minute = "0";
  else minute = "";
  if(timeinfo.tm_hour>12) {
    thr = timeinfo.tm_hour-12;
    hr = String(thr);
  }
  else hr = String(timeinfo.tm_hour);
  Display.print(hr + ":" + minute + String(timeinfo.tm_min));
}

WiFiManager wm;
bool res;

void setup()
{
  Serial.begin(115200);
  Display.begin();
  Display.setIntensity(0);
  //Display.displayClear();
  pinMode(TRIGGER_PIN,INPUT_PULLUP);
res = wm.autoConnect("Cams clock","password"); 
Display.print("trying to auto connect");
if(res){
  
  configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
  Display.print("good wifi");
  delay(4000);
    WiFi.disconnect(true);
  WiFi.mode(WIFI_OFF);
}
  }

void getTime(){
  Serial.println("got time");
  //init and get the time
  configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
  

  //disconnect WiFi as it's no longer needed
  WiFi.disconnect(true);
  WiFi.mode(WIFI_OFF);
}
bool btn = false;
bool wifiConnected = true;
void loop()
{
  Serial.println(digitalRead(TRIGGER_PIN));
  if ( digitalRead(TRIGGER_PIN) == LOW && !btn) {
    Serial.println("mm");
btn=true;
  }
  else if(btn) {
    btn=false;
    //reset settings - for testing
    //wm.resetSettings();
  
    // set configportal timeout
    wm.setConfigPortalTimeout(timeout);

    if (!wm.startConfigPortal("Cams clock")) {
      wifiConnected = true;
      Serial.println("failed to connect and hit timeout");
      delay(3000);
      //reset and try again, or maybe put it to deep sleep
      ESP.restart();
      delay(5000);
    }

    //if you get here you have connected to the WiFi
    Serial.println("connected...yeey :)");

  }
  if(wifiConnected) {
    wifiConnected=false;
    getTime(); 
    }
  delay(4000);
  printLocalTime();
}

[xfpd]

Does the first clock work with this code on the external power supply?

[marco_c]

You don't say what power supply you are using, but the MAX7219 does not work reliably with a 3V power supply. You need to give the matrix 5V for the LEDs. Remember to connect the ground of all the power supplies together to avoid other problems. You also need to make sure that you have enough power for the matrices (ie, the power supply from the MCU board just won't be enough).

For a small number of LED modules in the chain you might get away with 3V digital signals but the operation is usually marginal and may not work reliably. You should also really be using a signal level converter between ESP8266 and the MAX7219 I/O.

[brad3260]

Thank you both for the help. The first clock I made, I just ran a wire from the Vin of the ESP32 to the VCC of the matrix and had no problems. On this one, I just now ran an external power supply to the matrix and now it's working perfectly. I must have just gotten lucky with the first one.