M41T65(2004) 查看數據表（PDF） - STMicroelectronics

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M41T65
(Rev.:2004)

Serial Access Real-Time Clock with Alarms

STMicroelectronics 

Figure 13. M41T65 Block Diagram

XTAL

SDA

SCL

Note: 1. Open Drain.

32KHz

OSCILLATOR

I2C

INTERFACE

REAL TIME CLOCK

CALENDAR

OSCILLATOR FAIL OFIE

DETECT

FT

RTC W/ALARM AFE

WATCHDOG

M41T62/63/64/65

IRQ/FT/OUT(1)

WDO(1)

AI09193

OPERATION

The M41T6X clock operates as a slave device on

the serial bus. Access is obtained by implementing

a start condition followed by the correct slave ad-

dress (D0h). The 16 bytes contained in the device

can then be accessed sequentially in the following

order:

1. Tenths/Hundredths of a Second Register

2. Seconds Register

3. Minutes Register

4. Hours Register

5. Square Wave/Day Register

6. Date Register

7. Century/Month Register

8. Year Register

9. Calibration Register

10. Watchdog Register

11 - 15. Alarm Registers

16. Flags Register

2-Wire Bus Characteristics

The bus is intended for communication between

different ICs. It consists of two lines: a bi-direction-

al data signal (SDA) and a clock signal (SCL).

Both the SDA and SCL lines must be connected to

a positive supply voltage via a pull-up resistor.

The following protocol has been defined:

– Data transfer may be initiated only when the

bus is not busy.

– During data transfer, the data line must remain

stable whenever the clock line is High.

– Changes in the data line, while the clock line is

High, will be interpreted as control signals.

Accordingly, the following bus conditions have

been defined:

Bus not busy. Both data and clock lines remain

High.

Start data transfer. A change in the state of the

data line, from high to Low, while the clock is High,

defines the START condition.

Stop data transfer. A change in the state of the

data line, from Low to High, while the clock is High,

defines the STOP condition.

Data Valid. The state of the data line represents

valid data when after a start condition, the data line

is stable for the duration of the high period of the

clock signal. The data on the line may be changed

during the Low period of the clock signal. There is

one clock pulse per bit of data.

Each data transfer is initiated with a start condition

and terminated with a stop condition. The number

of data bytes transferred between the start and

stop conditions is not limited. The information is

transmitted byte-wide and each receiver acknowl-

edges with a ninth bit.

By definition a device that gives out a message is

called “transmitter,” the receiving device that gets

the message is called “receiver.” The device that

controls the message is called “master.” The de-

vices that are controlled by the master are called

“slaves.”

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