DS1305
NOTE:
CPHA bit polarity (if applicable) may need to be set accordingly. SERIAL CLOCK AS A FUNCTION
OF MICROCONTROLLER CLOCK POLARITY (CPOL) Figure 6
CE
SHIFT
INTERNAL STROBE
CPOL = 1
SCLK
CE
CPOL = 0
SCLK
SHIFT
INTERNAL STROBE
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
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DALLAS [ DALLAS SEMICONDUCTOR ]
