Real time clock

I want to get a real time clock running in my system. I have a linux 2.6.24 version. any suggestions?

Do you mean as a source for NTP?
Or is it for some other purpose that the PC hardware & Linux clocks don’t support?

I have linux running on an embedded board and I want a real time clock installed on the board.

Well actually I have been trying to give ntpsserver address to a system connected to the board so it takes the time from there. If i do an rdate -s <IP of system> It says rdate:connection refused

what do I do??

well I dont have the board and system connected to internet so I cant access any ntp servers…n for some reason the time n date of the board is all random value. since the system connected to it runs fine I thought i can synchronise the board’ time wth the system.

since this wasnt working I thought i could go for a realtime clock.

Sounds like good thinking, and you don’t need great accuracy.

According to rdate(1) rdate(1): time via network - Linux man page you need an RFC 868 time service. which appears to be time on port 37 both tcp & udp. TIME protocol - Wikipedia, the free encyclopedia suggests xinetd daemon can provide this. That’s lighter weight than NTP and naturally is FOSS, but there may be a lighter weight timeserver implementation more suitable, the RFC looks rather simple!

Presumbably synchronisation is more important than accuracy in the embedded system, though if time gets reset to past by a reboot you may have problem, but I guess you could push a time sync, on startup. The WIKI page on realtime clocks features a link to a software RTC based on a PIC controller.

NTP has features to operate in ‘orphan’ mode for disconnected networks Association Management

For setting time correctly I think the best info source is on NTP Reference Clocks