Datasheet

ADAU1381
Rev. B | Page 35 of 84
I
2
C Read and Write Operations
Figure 40 shows the timing of a single-word write operation.
Every ninth clock pulse, the ADAU1381 issues an acknowledge
by pulling SDA low.
Figure 41 shows the timing of a burst mode write sequence.
This figure shows an example where the target destination
registers are two bytes. The ADAU1381 knows to increment its
subaddress register every two bytes because the requested
subaddress corresponds to a register or memory area with a
2-byte word length.
The timing of a single-word read operation is shown in Figure 42.
Note that the first R/
W
bit is 0, indicating a write operation. This is
because the subaddress still needs to be written to set up the
internal address. After the ADAU1381 acknowledges the receipt
of the subaddress, the master must issue a repeated start command
followed by the chip address byte with the R/
W
bit set to 1 (read).
This causes the ADAU1381 SDA to reverse and begin driving
data back to the master. The master then responds every ninth
pulse with an acknowledge pulse to the ADAU1381.
Figure 43 shows the timing of a burst mode read sequence. This
figure shows an example where the target read registers are two
bytes. The ADAU1381 increments its subaddress every two bytes
because the requested subaddress corresponds to a register or
memory area with word lengths of two bytes. Other address
ranges may have a variety of word lengths ranging from one to
five bytes. The ADAU1381 always decodes the subaddress and
sets the auto-increment circuit so that the address increments
after the appropriate number of bytes.
S
AS
SUBADDRESS,
LOW BYTE
AS AS AS AS ... AS P
CHIP ADDRESS,
R/W = 0
DATA
BYTE 1
DATA
BYTE 2
DATA
BYTE N
SUBADDRESS,
HIGH BYTE
S = START BIT, P = STOP BIT, AS = ACKNOWLEDGE BY SLAVE.
SHOWS A ONE-WORD WRITE, WHERE EACH WORD HAS N BYTES.
08313-038
Figure 40. Single-Word I
2
C Write Sequence
S AS AS ASASASASAS ASAS
...
P
CHIP
ADDRESS,
R/W = 0
SUBADDRESS,
HIGH BYTE
SUBADDRESS,
LOW BYTE
DATA-WORD 1,
BYTE 1
DATA-WORD 1,
BYTE 2
DATA-WORD 2,
BYTE 1
DATA-WORD 2,
BYTE 2
DATA-WORD N,
BYTE 1
DATA-WORD N,
BYTE 2
S = START BIT, P = STOP BIT, AS = ACKNOWLEDGE BY SLAVE.
SHOWS AN N-WORD WRITE, WHERE EACH WORD HAS TWO BYTES. (OTHER WORD LENGTHS ARE POSSIBLE, RANGING FROM ONE TO FIVE BYTES.)
0
8313-039
Figure 41. Burst Mode I
2
C Write Sequence
S
AMAMAS AMAS SASAS
...
P
CHIP ADDRESS,
R/W = 0
CHIP ADDRESS,
R/W = 1
DATA
BYTE N
DATA
BYTE 2
DATA
BYTE 1
SUBADDRESS,
HIGH BYTE
SUBADDRESS,
LOW BYTE
S = START BIT, P = STOP BIT, AM = ACKNOWLEDGE BY MASTER, AS = ACKNOWLEDGE BY SLAVE.
SHOWS A ONE-WORD READ, WHERE EACH WORD HAS N BYTES.
08313-040
Figure 42. Single-Word I
2
C Read Sequence
S
SAS AS AS AS AMAM AMAM
...
P
CHIP
ADDRESS,
R/W = 0
SUBADDRESS,
HIGH BYTE
SUBADDRESS,
LOW BYTE
DATA-WORD 1,
BYTE 1
DATA-WORD 1,
BYTE 2
DATA-WORD N,
BYTE 1
DATA-WORD N,
BYTE 2
CHIP
ADDRESS,
R/W = 1
S = START BIT, P = STOP BIT, AM = ACKNOWLEDGE BY MASTER, AS = ACKNOWLEDGE BY SLAVE.
SHOWS AN N-WORD READ, WHERE EACH WORD HAS TWO BYTES. (OTHER WORD LENGTHS ARE POSSIBLE, RANGING FROM ONE TO FIVE BYTES.)
08313-041
Figure 43. Burst Mode I
2
C Read Sequence