DS1306_05 Datasheet, PDF (13/21 Pages) Dallas Semiconductor – Serial Alarm Real-Time Clock

Figure 8. SPI MULTIPLE-BYTE BURST TRANSFER
DS1306
READING AND WRITING IN BURST MODE
Burst mode is similar to a single-byte read or write, except that CE is kept high and additional SCLK
cycles are sent until the end of the burst. The clock registers and the user RAM may be read or written in
burst mode. When accessing the clock registers in burst mode, the address pointer will wrap around after
reaching 1Fh (9Fh for writes). When accessing the user RAM in burst mode, the address pointer wraps
around after reaching 7Fh (FFh for writes).
3-WIRE INTERFACE
The 3-wire interface mode operates similar to the SPI mode. However, in 3-wire mode there is one I/O
instead of separate data in and data out signals. The 3-wire interface consists of the I/O (SDI and SDO
pins tied together), CE, and SCLK pins. In 3-wire mode, each byte is shifted in LSB first, unlike SPI
mode, where each byte is shifted in MSB first.
As is the case with the SPI mode, an address byte is written to the device followed by a single data byte
or multiple data bytes. Figure 9 illustrates a read and write cycle. In 3-wire mode, data is input on the
rising edge of SCLK and output on the falling edge of SCLK.
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