World time clock with Uno and multiple MAX7219 7 segment display.

Using Arduino Project Guidance
1

I was hoping to put together a World time clock using a Uno (or clone) and a bunch of MAX7219 7 segment displays.

Each display showing the time in different cities around the world.

I have done a search and nothing stood out. Is this indeed possible? Maybe getting the time from an NTP server?

Thanks in advance.

2

We did a project to get time from an NTP server. Took more memory than Uno had, ended up using '1284P chip instead.

Driving multiple MAX7219 for all the 5V digits you want is not a problem.

3

CrossRoads:
We did a project to get time from an NTP server. Took more memory than Uno had, ended up using '1284P chip instead.

Driving multiple MAX7219 for all the 5V digits you want is not a problem.

Excellent. Thanks for your help.

4

norbsy:
I was hoping to put together a World time clock using a Uno (or clone) and a bunch of MAX7219 7 segment displays.

Each display showing the time in different cities around the world.

I have done a search and nothing stood out. Is this indeed possible? Maybe getting the time from an NTP server?

Thanks in advance.

Use a DS3231 to get the time.
For the "world time" stuff, just do arithmetic. The Arduino Uno is more than capable of simple arithmetic. The only hard part is Daylight Saving Time. For that, maybe the best way to go would be to store tables of Daylight Saving Time changeover dates for different countries and calculate based on that.

To be honest, this is a bit of an advanced project. You will probably want use something called PROGMEM to store the tables of dates.

How many time zones do you want to display, and for which countries?

5

"To be honest, this is a bit of an advanced project. "
If using NTP server, yes. If using DS3231, no.

6

There is an example NTP time sketch in the Ethernet examples that come with the IDE.

7

norbsy:
I was hoping to put together a World time clock using a Uno (or clone) and a bunch of MAX7219 7 segment displays.

Each display showing the time in different cities around the world.

I have done a search and nothing stood out. Is this indeed possible? Maybe getting the time from an NTP server?

Each NTP time server woldwide serves the time with timestaps using the same time zone: UTC time

So whether you are creating a "world time clock" by using a RTC module or by using a NTP time server, you will have to calculate each local time from UTC time to local time:

  • you have to consider the time zone
  • and you have to consider local "summertime" switching algorithms
8

jurs:

  • and you have to consider local "summertime" switching algorithms

That can be tricky.

9

Time zones are no problem with Christensen's Time Zone Library.

10

aarg:
Time zones are no problem with Christensen's Time Zone Library.

I just noticed that one of his examples is a world clock, but it prints to the Serial monitor rather than to LED displays. Still, that sounds like one step closer to a solution for the OP.

11

odometer:
I just noticed that one of his examples is a world clock, but it prints to the Serial monitor rather than to LED displays. Still, that sounds like one step closer to a solution for the OP.

Thanks for that. I will see if I can wrap my tiny brain around all the info i have been given.

Really appreciate the help.