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XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
Real Time Clock
User’s Manual
15-1
V2.2, 2004-01
RTC_X8, V2.1
15
Real Time Clock
The Real Time Clock (RTC) module of the XC161 basically consists of a chain of
prescalers and timers. Its count clock is derived from the auxiliary oscillator or from the
prescaled main oscillator. The RTC serves various purposes:
•
48-bit timer for long term measurements
•
System clock to determine the current time and date
(the RTC’s structure supports the direct representation of time and date)
•
Cyclic time based interrupt (can be generated by any timer of the chain)
A number of programming options as well as interrupt request signals adjust the
operation of the RTC to the application’s requirements. The RTC can continue its
operation while the XC161 is in a power-saving mode, such that real time date and time
information is provided.
Figure 15-1
SFRs Associated with the RTC Module
The RTC module consists of a chain of 3 divider blocks:
•
a selectable 8:1 divider (on - off)
•
the reloadable 16-bit timer T14
•
the 32-bit RTC timer block (accessible via RTC_RTCH and RTC_RTCL), made of:
– the reloadable 10-bit timer CNT0
– the reloadable 6-bit timer CNT1
– the reloadable 6-bit timer CNT2
– the reloadable 10-bit timer CNT3
All timers count upwards. Each of the five timers can generate an interrupt request. All
requests are combined to a common node request.
Note: The RTC registers are not affected by a system reset in order to maintain the
correct system time even when intermediate resets are executed.
m c a 0 4 4 63 _ x c .v s d
R T C _ C O N
R T C _T 1 4R E L
R T C _ T 14
R T C _IS N C
C o ntro l R eg is te rs
D a ta R eg is te rs
C o un ter R eg is te rs
In terru pt C o n tro l
R T C _ T 14
T im er T 14 C o un t R e giste r
R T C _ T 14 R E L T im er T 14 R e lo a d R e g is te r
R T C _ R T C H /L R T C C o un t R e gisters , H igh /L o w
R T C _ R E LH /L
R T C R e lo a d R e g ., H ig h/L ow
R T C _IC
E
E
E
R T C _ R T C H
E
R T C _ R T C L
E
E
R T C _ C O N
R e al T im e C lo ck C on tro l R e gister
S Y S C O N 0
G en e ral S ys te m C on tro l R e gister
S Y S C O N 3
P o w e r M an a ge m e nt C o ntro l R eg .
R T C _ IS N C
Interru pt S u b no de C o ntro l R eg is te r
R T C _ IC
R T C In te rru pt C o ntro l R eg is ter
E
R T C _R E L H
E
R T C _R E L L
E
S Y S C O N 3
E
S Y S C O N 0
E