Synchronise RTC from NTP server

Dear friends i am having a System on module having arm processor and external rtc on it. The system is having embeded linux installed on it. I want to synchronise the RTC time from a NTP server on the network. How can i do this . Plese suggest possible soln with C code.
Thanking You all in advance.

Hi,

Originally Posted by cdr_nitjsr@yahoo.com Dear friends i am having a System on module having arm processor and external rtc on it. The system is having embeded linux installed on it. I want to synchronise the RTC time from a NTP server on the network. How can i do this . Plese suggest possible soln with C code. Thanking You all in advance.

You could use 'ntpd' and cron job to update the time via a script;

#!/bin/sh
#11-06-06 gws use ntp
 /usr/sbin/ntpdate -v 0.us.pool.ntp.org ntp-1.mcs.anl.gov ntp-2.mcs.anl.gov &&hwclock --systohc
#--hctosys


#/usr/sbin/netdate time.mtco.com && /sbin/hwclock --systohc

No need to write 'c" to re-invent a function that is readily available. I place the above script in my '/etc/cron.hourly' as 'time' to update time. Be sure to make the 'time' script 'x' via chmod a+x /etc/cron.hourly/time
Hope this helps.
Have fun & enjoy!

Originally Posted by onebuck Hi, You could use 'ntpd' and cron job to update the time via a script; #!/bin/sh #11-06-06 gws use ntp /usr/sbin/ntpdate -v 0.us.pool.ntp.org ntp-1.mcs.anl.gov ntp-2.mcs.anl.gov &&hwclock --systohc #--hctosys #/usr/sbin/netdate time.mtco.com && /sbin/hwclock --systohc No need to write 'c" to re-invent a function that is readily available. I place the above script in my '/etc/cron.hourly' as 'time' to update time. Be sure to make the 'time' script 'x' via chmod a+x /etc/cron.hourly/time Hope this helps. Have fun & enjoy!

Thank u for replying. I got some idea but my BSP package has given API like GetExtRTCTime and SetExtRTCTime. If i use ntpd to synch how can i use these api to get and set time of RTC. Plz suggest thanking you.

Not enough information provided but if the system came with the RTC as a package or as an option then it might already be configured, nothing special is required and the above should work. Is there a kernel driver for the RTC?

Hi,

Originally Posted by cdr_nitjsr@yahoo.com Thank u for replying. I got some idea but my BSP package has given API like GetExtRTCTime and SetExtRTCTime. If i use ntpd to synch how can i use these api to get and set time of RTC. Plz suggest thanking you.

I agree with michaelk. If the RTC has support by the kernel then you can use 'nptd'. Simple & easy to do. You should check that systems documentation for information as to how the RTC is handled.
Hope this helps.
Have fun & enjoy!