DS1305

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NOTE:

CPHA bit polarity (if applicable) may need to be set accordingly. SERIAL CLOCK AS A FUNCTION

OF MICROCONTROLLER CLOCK POLARITY (CPOL) Figure 6

NOTE:

CPOL is a bit that is set in the microcontroller’s Control Register.

ADDRESS AND DATA BYTES

Address and data bytes are shifted MSB first into the serial data input (SDI) and out of the serial data

output (SDO). Any transfer requires the address of the byte to specify a write or read to either a RTC or

RAM location, followed by one or more bytes of data. Data is transferred out of the SDO for a read

operation and into the SDI for a write operation (see Figure 7 and 8).

SPI SINGLE-BYTE WRITE Figure 7

CE

CPOL = 1

SCLK

INTERNAL STROBE

SHIFT

CE

CPOL = 0

SCLK

INTERNAL STROBE

SHIFT