Rainbow-electronics DS1672 Instrukcja Użytkownika Pobierz pdf (Strona 7)

DS1672

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OPERATION

The block diagram in Figure 4 shows the main elements of the DS1672. As shown, communications to

and from the DS1672 occur serially over a 2-wire, bidirectional bus. The DS1672 operates as a slave

device on the serial bus. Access is obtained by implementing a START condition and providing a device

identification code followed by a register address. Subsequent registers can be accessed sequentially until

a STOP condition is executed.

Figure 4. Block Diagram

Clock Accuracy

The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the match

between the capacitive load of the oscillator circuit and the capacitive load for which the crystal was

trimmed. Additional error will be added by crystal frequency drift caused by temperature shifts. External

circuit noise coupled into the oscillator circuit may result in the clock running fast. Refer to Application

Note 5: “Crystal Considerations with Dallas Real-Time Clocks” for detailed information.

Address Map

The counter is accessed by reading or writing the first 4 bytes of the DS1672 (00h–03h). The control

in Table 1. If the master continues to send or request more data after the address pointer has reached 05h,

the address pointer will wrap around to location 00h.

Table 1. Registers

ADDRESS B7 B6 B5 B4 B3 B2 B1 B0 FUNCTION

00h LSB Counter Byte 1

01h Counter Byte 2

02h Counter Byte 3

03h MSB Counter Byte 4

04h

EOSC

Control

05h TCS TCS TCS TCS DS DS RS RS Trickle Charger

32-BIT

COUNTER

(4 BYTES)

SERIAL BUS

INTERFACE

OSCILLATOR

AND DIVIDER

POWER

CONTROL

ADDRESS

CONTROL

LOGIC

BACKUP

GND

SCL

SDA

CONTROL

TRICKLE CHARGER

RST

1 2 3 4 5 6 7 8 9 10 11 12

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