I found a way to "talk" to NJU6355 RTC chip.
Here are read and write subs for it:

settime:
IO = 1
CE = 1
ShiftOut SDATA, CLK, LSBFIRST, [rtcyear, rtcmonth, rtcdate, rtcday\4, rtchr, rtcmin]
CE = 0
Return
gettime:
IO = 0
CE = 1
ShiftIn SDATA, CLK, LSBPRE, [rtcyear, rtcmonth, rtcdate, rtcday\4, rtchr, rtcmin, rtcsec]
CE = 0
Return

Nick