Digital clock code with NTP sync for Arduino Nano 33 IoT and MAX7219 LED matrix

• Grab a device (computer/phone/tablet) with WiFi connectivity.
• Hold Select for 5 seconds (or enter 'a' in the serial monitor).
• If the clock is not connected to WiFi, it will display 7777 and broadcast a WiFi access point called “Clock”. Connect your device to “Clock” and browse to 7.7.7.7.
• If the clock is connected to WiFi, it will flash its IP address (as a series of three 4-digit numbers). With your device on the same WiFi network, browse to that IP address.
  • To disconnect the clock from WiFi, hold Select for 15 seconds; it will revert to the “Clock” access point.
• For security, the clock will stop serving the settings page (and “Clock” access point if applicable) after 2 minutes of inactivity.