AD7879 datasheet(34/36 Pages) AD

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AD7879

Rev. 0 | Page 34 of 36

NOTES

1. A START CONDITION AT THE BEGINNING IS DEFINED AS A HIGH-TO-LOW TRANSITION ON SDA WHILE SCL REMAINS HIGH.

2. A STOP CONDITION AT THE END IS DEFINED AS A LOW-TO-HIGH TRANSITION ON SDA WHILE SCL REMAINS HIGH.

3. THE MASTER GENERATES THE ACK AT THE END OF THE READBACK TO SIGNAL THAT IT DOES NOT WANT ADDITIONAL DATA.

4. 7-BIT DEVICE ADDRESS [DEV A6:DEV A0] = [0 1 0 1 1 X X], WHERE THE TWO LSB Xs ARE DON'T CARE BITS.

5. REGISTER DATA [D15:D8] AND REGISTER DATA [D7:D0] ARE ALWAYS SEPARATED BY A LOW ACK BIT.

6. THE R/W BIT IS SET TO A1 TO INDICATE A READBACK OPERATION.

SDA

DEV

R/W

SCL

DEV

ACK

910

START

AD7879-1 DEVICE ADDRESS

ACK

DEV

AD7879 DEVICE ADDRESS

AD7879-1 DEVICE ADDRESS

DEV

R/W

ACK

AD7879-1 DEVICE ADDRESS

DEV

R/W

USING

REPEATED

START

SEPARATE

READ AND

WRITE

TRANSACTIONS

ACK

Figure 43. Example of I2C Timing for Single Register Read Back Operation

6-BIT DEVICE

ADDRESS

6-BIT DEVICE

ADDRESS

[7:0]

READ DATA

HIGH BYTE [15:8]

READ DATA

LOW BYTE [7:0]

READ DATA

HIGH BYTE [15:8]

READ DATA

LOW BYTE [7:0]

. . .

READ (WRITE TRANSACTION SETS UP REGISTER ADDRESS)

6-BIT DEVICE

ADDRESS

6-BIT DEVICE

LOW BYTE

[7:0]

READ DATA

ADDRESS

READ DATA

HIGH BYTE [15:8]

READ DATA

HIGH BYTE [15:8]

READ DATA

LOW BYTE [7:0]

. . .

READ (USING REPEATED START)

6-BIT DEVICE

ADDRESS

[7:0]

WRITE DATA

HIGH BYTE [15:8]

WRITE DATA

LOW BYTE [7:0]

WRITE DATA

HIGH BYTE [15:8]

WRITE DATA

LOW BYTE [7:0]

. . .

WRITE

OUTPUT FROM MASTER

OUTPUT FROM AD7879

S = START BIT

P = STOP BIT

SR = REPEATED START BIT

R = READ BIT

W = WRITE BIT

ACK = ACKNOWLEDGE BIT

ACK = NO ACKNOWLEDGE BIT

Figure 44. Example of Sequential I2C Write and Read Back Operation

AD7879 Datasheet(PDF) 34 Page - Analog Devices

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