
4- 40
MC68341 USER’S MANUAL
MOTOROLA
4.4.3 RTC Control/Status Register (RCR)
The RCR contains the control bits for the RTC.
RCR
$0C8
76543210
WR_ERR
ALARM
ERRMUX
ROS1
ROS0
AIE/ C
RCK_HT
SET
RESET:
U
0000000
Supervisor Only
WR_ERR—RTC Write Error Indicator
1 = An error has occurred in the contents of the time registers.
0 = No error in the contents of the time registers.
Any illegal combination in the time registers sets this bit, e.g., seconds greater than 59,
hours greater than 23, non-BCD data, or day exceeding the maximum for the month
selected.
ALARM—RTC Alarm Indicator
1 = Alarm has occurred. In alarm indicator latched mode, this bit remains set until
AIE/C is cleared. In alarm indicator pulsed mode, this bit clears on reading the
RCR.
0 = No alarm condition.
ERRMK—RTC Write Error Mask
1 = Enables the interrupt output from the WR_ERR indicator.Masks the interrupt
output from the WR_ERR indicator.
0 = Masks the interrupt output from the WR_ERR indicator.
ROS1, ROS0—RTC Output Select
00 = Alarm indicator latched. RTCOUT is asserted high when the alarm register
matches the time, and negated low by clearing the AIE/C bit.
01 = Alarm indicator pulsed. RTCOUT is asserted high when the alarm register
matches the time, and negated low one RTC clock (30.5
S) later. RTCOUT
can also be negated by clearing the AIE/C bit.
10 = Square wave. RTCOUT drives a 1.024 KHz square wave (RTC clock
÷ 32)
11 = Alarm indicator latched inverted. RTCOUT is asserted low when the alarm
register matches the time, and negated high by clearing the AIE/C bit.
AIE/C—Alarm Indicator Enable/Clear
1 = Alarm indicator bit can assert
0 = Alarm indicator bit cannot assert. Clearing this bit clears the alarm condition and
negates RTCOUT if programmed as an alarm indicator.
RCK_HT—RTC Clock Halt
1 = RTC clock is stopped
0 = RTC clock runs.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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