DS80C320-ECD DALLAS [Dallas Semiconductor], DS80C320-ECD Datasheet - Page 158

• Manufacturer Part Number: DS80C320-ECD
• Description: High-Speed Microcontroller User Guide
• Manufacturer: DALLAS [Dallas Semiconductor]

SECTION 14: REAL-TIME CLOCK
The DS87C530 incorporates a real-time clock (RTC) onto the High-Speed Microcontroller family core.
This allows the device to perform real-time related functions such as data logging and time-stamping
without an external timer. In addition, the RTC includes an alarm function which can execute a software
interrupt or resume operation from Stop mode at a specified time. The RTC features are controlled by 12
new SFRs. These registers, as well as two new interrupt control bits are shown in Table 14-1.
REAL-TIME CLOCK CONTROL AND STATUS BIT SUMMARY Table 14-1
The RTC control and status registers can be subdivided into 4 groups: RTC time registers (RTCSS;FAh,
RTCS;FBh, RTCM;FCh, RTCH;FDh, RTCD0;FEh, RTCD1;FFh), RTC alarm registers (RTASS;F2h,
RTAS;F3h, RTAM;F4h, RTAH;F5h), RTC calibration (TRIM;96h), and RTC control (RTCC;F9h).
STARTING AND STOPPING THE RTC
Operation of the RTC is enabled by setting the RTC Enable bit, RTCE (RTCC.0) to 1. This will start the
RTC crystal amplifier, and begin clocking the RTC. Like all crystal oscillators, the RTC crystal oscillator
has a crystal warm-up period. Software should allow a minimum of 1 second between setting the RTCE
bit to 1 and initializing the time. This allows the clock to be guaranteed stable when timekeeping begins.
ERTCI
PRTCI
RTASS.7–0
RTAS.5–0
RTAM.5–0
RTAH.4–0
RTCSS.7–0
RTCS.5–0
RTCM.5–0
RTCH.4–0
DOW.2–0
RTCD1.7–0
RTCD0.7–0
SRCE
SCE
MCE
HCE
RTCRE
RTCWE
RTCIF
RTCE
E4K
X12/6
TRM2–0
BIT NAME
EIE.5
EIP.5
RTASS
RTAS
RTAM
RTAH
RTCSS
RTCS
RTCM
RTCH.4–0
RTCH.7–5
RTCD1, (MSB)
RTCD0, (LSB)
RTCC.7
RTCC.6
RTCC.5
RTCC.4
RTCC.3
RTCC.2
RTCC.1
RTCC.0
TRIM.7
TRIM.6
TRIM.5
TRIM.3
TRIM.1
LOCATION
RTC Interrupt Enable
RTC Interrupt Priority
RTC Alarm Subsecond
RTC Alarm Second
RTC Alarm Minute
RTC Alarm Hour
RTC Subsecond
RTC Second
RTC Minute
RTC Hour
RTC Day of Week
RTC Day
RTC Subsecond
Compare Enable
RTC Second Compare
Enable
RTC Minute Compare
Enable
RTC Hour Compare
Enable
RTC Read Enable
RTC Write Enable
RTC Interrupt Flag
RTC Enable
External 4096 Hz RTC
Signal Enable
RTC Crystal Capaci-
tance Select
RTC Trim Bit 2–0
FUNCTION
158 of 175
0–FFFFh
RANGE
0–3Bh
0–3Bh
0–17H
0–3Bh
0–3Bh
0–FFh
0–FFh
0–17h
0–7h
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
RESET
0
0
0
0
0
High-Speed Microcontroller User’s Guide
Unrestricted
Unrestricted
Unrestricted
Unrestricted
Unrestricted
Unrestricted
Read: only if RTCRE=1.
Cannot be written. Cleared
when RTCWE 1–>0
Read: only if RTCRE=1.
Write: only if RTCWE=1.
1.95 ms Read/Write window
Unrestricted
Unrestricted
Unrestricted
Unrestricted
Unrestricted
Read: Unrestricted
Write: Timed Access
Unrestricted
Read: Unrestricted
Write: Timed Access
Read: Unrestricted
Write: Timed Access
READ/WRITE ACCESS