XC2200 Derivatives
System Units (Vol. 1 of 2)
Architectural Overview
User’s Manual
2-22
V2.1, 2008-08
ArchitectureX22, V1.1
Real Time Clock (RTC)
The Real Time Clock (RTC) module of the XC2200 is directly clocked wih a separate
clock signal. Several internal and external clock sources can be selected via register
RTCCLKCON. It is, therefore, independent from the selected clock generation mode of
the XC2200.
The RTC basically consists of a chain of divider blocks:
• Selectable 32:1 and 8:1 dividers (on - off)
• The reloadable 16-bit timer T14
• The 32-bit RTC timer block (accessible via registers RTCH and RTCL), made of:
– a reloadable 10-bit timer
– a reloadable 6-bit timer
– a reloadable 6-bit timer
– a reloadable 10-bit timer
All timers count up. Each timer can generate an interrupt request. All requests are
combined to a common node request.
Note: The registers associated with the RTC are not affected by an application reset in
order to maintain the contents even when intermediate resets are executed.
The RTC module can be used for different purposes:
• System clock to determine the current time and date
• Cyclic time based interrupt, to provide a system time tick independent of CPU
frequency and other resources
• 48-bit timer for long term measurements
• Alarm interrupt for wake-up on a defined time