Here are some codes to customize your The City Clock.
click here to get the original version of the code.
click here to get a custom version that will only display the hour column during the night (to lower luminosity)
click here to get a custom version that will shut down the clock between midnight and 8 am
click here to get an AM/PM version of the clock
How to change the code of the City Clock
Steps to follow to change the code of the clock :
Download the Arduino software
Add the DS3231 library and import the .zip file from the Arduino software (Add a library tab) Choose one of the available code above
Copy/Paste the code in a new file inside the Arduino software. (first remove everything in the new file, then copy/paste the entire new code)
Connect the Arduino of the clock to your computer with the USB cable (no need to remove the Arduino from the clock)
Make sure to select the right board in the menu (normally it should be automatic but sometimes it does not work). The type of board should be "Arduino Nano" and the port something like usbserialXXXX
Hit the => button in the toolbar of the editor to transfer the code
Wait for your code to upload
Your clock is ready, you can plug it back somewhere else !
If your serial port is not showing up as an option in the Arduino app, try a different USB cable. Some USB cables support charging only, and can not be used for communication. The USB cable that came with your clock should support USB communication, so use that if you are having problems with your other cables.
If uploading is failing, you might need to change your processor to "ATmega328P (Old Bootloader)". For more details, see: https://support.arduino.cc/hc/en-us/articles/360016785580-Error-avrdude-stk500-getsync-attempt-X-of-10-not-in-sync-resp-.