Dear Gary and All,
I have add to one hardware RTC DS3231 to my system. It working fine on i2c connection.
I think that I have a wrong parameter in /etc/ntp.conf file, because when I start my system and gps is not ready, the system time was changed in a wrong time.
here my /etc/ntp.conf
# GPS PPS reference (NTP1)
server 127.127.28.1 minpoll 4 maxpoll 4 prefer true
fudge 127.127.28.1 refid PPS
fudge 127.127.28.1 flag1 1
# GPS Serial data reference (NTP0)
server 127.127.28.0 minpoll 4 maxpoll 4
fudge 127.127.28.0 time1 0.9999 refid GPS
Max