Max7219 clock NTP 12 hour format

[romeomart]

Hello, I am using an ESP32 to control a max7129, everything works as expected, except for I am trying to display the time in a 12 hour format and I cannot figure it out

#include <WiFi.h>
#include <NTPClient.h>
#include <WiFiUdp.h>
#include <MD_Parola.h>
#include <MD_MAX72xx.h>
#include <SPI.h>

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

#define USE_12HR_FORMAT true

#define MAX_DEVICES 6
#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);

WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP);

const char* ssid     = "rmphone";
const char* password = "qcin1085";

String Time, hour, minute, second;
String Formatted_date;
long currentMillis = 0;
long previousMillis = 0;
int interval = 1000;

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print("Connecting.");
  }
  Serial.println("");
  Serial.println("WiFi connected.");

  timeClient.begin();
  timeClient.setTimeOffset(-21600);
  
  Display.begin();
  Display.setIntensity(5);
  Display.displayClear();

}

void loop()
 {
   obtainTime();
}

void obtainTime() {
  while(!timeClient.update()) {
    timeClient.forceUpdate();
  }

  currentMillis = millis();

  if (currentMillis - previousMillis > interval)  {
previousMillis = millis();

Formatted_date = timeClient.getFormattedDate();
Serial.println(Formatted_date);

hour = Formatted_date.substring(11, 13);
minute = Formatted_date.substring(14, 16);
second = Formatted_date.substring(17, 19);


Time = hour + ":" + minute + ":" + second;
Serial.println(Time);
Display.setTextAlignment(PA_CENTER);
Display.print(Time);

}
}   

[anon73444976]

Are you saying you don't know how 12 hour time works?
What's the problem?

(This isn't an installation or troubleshooting issue, please move it to programming or ask a moderator to do it for you)

[anon57585045]

1. Never publish your wifi credentials.
2. I don't see any attempt to deal with 12 hour time in the sketch you posted.

[Grumpy_Mike]

Installation and Troubleshooting is for Problems with the Arduino itself NOT your project. It says so in the description of the section. Therefore I have moved your post here. Please be more careful where you post in future.

You may want to read this before you proceed:-
how to get the best out of this forum

[ruilviana]

@romeomart

hour = Formatted_date.substring(11, 13);
minute = Formatted_date.substring(14, 16);
second = Formatted_date.substring(17, 19);

Try this line after separating the hour/minute/second.

hour = hour.toInt()%12;

looking like this:

    hour = Formatted_date.substring(11, 13);
    minute = Formatted_date.substring(14, 16);
    second = Formatted_date.substring(17, 19);
    hour  = hour.toInt()%12;

I tested it here and it worked correctly.

[romeomart]

Thank you very much, it works well.

[Paul_B]

Are "String"s going to work in this application?

[anon57585045]

@ruilviana

hour = hour.toInt()%12;

Neither 12am nor 12pm is represented as 0 in the 12 hour system.

[ruilviana]

@romeomart

hour = Formatted_date.substring(11, 13);
minute = Formatted_date.substring(14, 16);
second = Formatted_date.substring(17, 19);

Hi,
in order to avoid future problems, modify your sketch to look like this:

    hour = Formatted_date.substring(11, 13);
    minute = Formatted_date.substring(14, 16);
    second = Formatted_date.substring(17, 19);

    if ((hour.toInt() == 0) or (hour.toInt() == 12)) {        // Use 12 instead of 0
      hour = String(12);
    }
    else {
      hour  = String(hour.toInt() % 12);                // Use String
    }

    Time = hour + ":" + minute + ":" + second;