TMPR4925 datasheet(551/590 Pages) TOSHIBA

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Chapter 19 Real Time Clock (RTC)

19-3

19.3 Operations

19.3.1

Operation

The RTC contains five 8-bit ripple counters connected in series. The first counter counts on each

C32K clock, while each successive counter only counts when the previous count stage has reached a

count of “0xFF”. Once the counters reach a count of “0xFFFFFFFFFFF”, the RTCINT interrupt will

assert to indicate that the counter is “rolling over”. Given a 44-bit counter for the RTC and an input

clock C32K of 32.768 kHz, the time until RTCINT interrupt will assert is 6213 days.

The software can generate an alarm interrupt(ALARMINT) by setting the ALARM[43:0] bits in the

Alarm Register.

Whenever the RTC becomes equal to the value set in the Alarm Register, the

ALARMINT will be triggered. The value of the RTC counter can be read via the RTC Register.

19.3.2

Interrupt

The RTC has two types interrupt sources. OR signal of them connects to the internal Interrupt

Controller (IRC).

Please check RTC Interrupt Status Register (RTCINT) to know which type of

interrupt occurred.

Type

Status Bits

Mask-able Bit

RTCINT

RTCINT in RTCINT

DSRTCINT in RTCCTRL

ALARMINT

ALARMINT in RTCINT

DSALINT in RTCCTRL

RTCINT:

This interrupt is set 44 bits of the RTC counter reach a value of “0xFFFFFFFFFFF” to alert the

software that the counter is “rolling over”.

ALARMINT:

This interrupt is set whenever the RTC counter reaches a count that is equal to the value of the

ALARM[43:0] bits set in the ALAMHI and ALARMLO Registers.

19.4 Registers

All registers should be accessed only as full word (32-bit) accesses. Any other type of access produces an

undefined result. Please write “0” to the undefined bit.

Table 19.4.1 RTC Module Registers

Reference

Address

Bit Width

19.4.1

0xF900

32-bit

RTCHI

RTC Register (High)

19.4.2

0xF904

32-bit

RTCLO

RTC Register (Low)

19.4.3

0xF908

32-bit

ALARMHI

Alarm Register (High)

19.4.4

0xF90C

32-bit

ALARMLO

Alarm Register (Low)

19.4.5

0xF910

32-bit

RTCCTRL

RTC Control Register

19.4.6

0xF914

32-bit

RTCINT

RTC Interrupt Status Register

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