Alarm Register (Rtcalrm); Rtc Control Register (Rtcctl) - Motorola DragonBall MC68328 User Manual

MINUTES
These 6 bits, when read, indicate the current minute and can be set to any value between
0 and 59.
SECONDS
These 6 bits, when read, indicate the current second and can be set to any value between
0 and 59.

5.1.4.2 ALARM REGISTER (RTCALRM).

31 30 29 28
Unused
15 14 13 12
Address: $(FF)FFFB04
The hours, minutes, and seconds can be read or written at any time. After a write, the current
time assumes the new values. Unused bits read 0.
HOURS
These 5 bits, when read, indicate the current setting of the alarm's hour and can be set to
any value between 0 and 23.
MINUTES
These 6 bits, when read, indicate the current setting of the alarm's minute and can be set
to any value between 0 and 59.
SECONDS
These 6 bits, when read, indicate the current setting of the alarm's second and can be set
to any value between 0 and 59.

5.1.4.3 RTC CONTROL REGISTER (RTCCTL).

15 14 13 12
UNUSED
ADDRESS: $(FF)FFFB0C
ENABLE RTC Enable
This bit enables the RTC.
1 = Enable RTC
0 = Disable RTC
38.4 38.4 kHz Reference Select
1 = Reference frequency is 38.4 kHz
0 = Reference frequency is 32.768 kHz
MOTOROLA MC68328 DRAGONBALL PROCESSOR USER'S MANUAL
27 26 25 24
HOURS
11 10 9 8
Unused
Figure 5-3. Alarm Register
11 10 9 8
Figure 5-4. Control Register
23 22 21 20
Unused
7 6 5 4
7 6 5 4
ENABLE 38.4
UNUSED
Real-Time Clock
19 18 17 16
MINUTES
3 2 1 0
SECONDS
Reset Value: $00000000
3 2 1 0
RESERVED
Reset Value: $0000
5-3