Real-Time Counter (RTC)
MCF51CN128 Reference Manual, Rev. 6
12-3
Freescale Semiconductor
12.1.3
Block Diagram
The block diagram for the RTC module is shown in
.
Figure 12-1. Real-Time Counter (RTC) Block Diagram
12.2
External Signal Description
The RTC does not include any off-chip signals.
12.3
Register Definition
The RTC includes a status and control register, an 8-bit counter register, and an 8-bit modulo register.
Refer to the direct-page register summary in
” for the absolute address assignments
for all RTC registers.This section refers to registers and control bits only by their names and relative
address offsets.
is a summary of RTC registers.
Table 12-1. RTC Register Summary
Name
7
6
5
4
3
2
1
0
RTCSC
R
RTIF
RTCLKS
RTIE
RTCPS
W
RTCCNT
R
RTCCNT
W
RTCMOD
R
RTCMOD
W
Clock
Source
Select
Prescaler
Divide-By
8-Bit Counter
(RTCCNT)
8-Bit Modulo
(RTCMOD)
8-Bit Comparator
RTIF
RTIE
Background
V
DD
RTC
Interrupt
Request
D
Q
R
E
LPO
RTC
Clock
Mode
ERCLK
IRCLK
RTCLKS
Write 1 to
RTIF
RTCPS
RTCLKS[0]