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TRANSFERRING DATA

Every byte put on the SDA line must be eight bits long, with

the most significant bit (MSB) being transferred first. The

number of bytes that can be transmitted per transfer is

unrestricted. Each byte of data has to be followed by an

acknowledge bit. The acknowledge related clock pulse is

generated by the master. The transmitter releases the SDA

line (HIGH) during the acknowledge clock pulse. The re-

ceiver must pull down the SDA line during the 9th clock

pulse, signifying an acknowledge. A receiver which has been

addressed must generate an acknowledge after each byte

has been received.

After the START condition, I

This address is seven bits long followed by an eighth bit

which is a data direction bit (R/W). For the eighth bit, a “0”

indicates a WRITE and a “1” indicates a READ. The second

byte selects the register to which the data will be written. The

third byte contains data to write to the selected register.

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W = write (SDA = “0”)

r = read (SDA = “1”)

ack = acknowledge (SDA pulled down by either master or slave)

rs = repeated startxx=36h

However, if a READ function is to be accomplished, a WRITE function must precede the READ function, as shown in the read

cycle waveform.

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