AD8191 datasheet(17/32 Pages) AD

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AD8191

Rev. 0 | Page 17 of 32

START

FIXED PART

ADDR

FIXED PART

ADDR

DATA

STOP

ACK

ADDR

ACK

R/W

ADDR

ACK

R/W

9 10 11

I2C_SCL

GENERAL CASE

I2C_SDA

EXAMPLE

I2C_SDA

Figure 30. I2C Read Diagram

READ PROCEDURE

To read data from the AD8191 register set, an I2C master (such

as a microcontroller) needs to send the appropriate control

signals to the AD8191 slave device. The signals are controlled

by the I2C master, unless otherwise specified. For a diagram of

the procedure, see Figure 30. The steps for a read procedure are

as follows:

Send a start condition (while holding the I2C_SCL line

high, pull the I2C_SDA line low).

Send the AD8191 part address (seven bits). The upper four

bits of the AD8191 part address are the static value [1001]

and the three LSBs are set by Input Pin I2C_ADDR2, Input

Pin I2C_ADDR1, and Input Pin I2C_ADDR0 (LSB). This

transfer should be MSB first.

Send the write indicator bit (0).

Wait for the AD8191 to acknowledge the request.

Send the register address (eight bits) from which data is to

be read. This transfer should be MSB first.

Wait for the AD8191 to acknowledge the request.

Send a repeated start condition (Sr) by holding the

I2C_SCL line high and pulling the I2C_SDA line low.

Resend the AD8191 part address (seven bits) from Step 2.

The upper four bits of the AD8191 part address are the

static value [1001] and the three LSBs are set by the Input

Pin I2C_ADDR2, I2C_ADDR1 and Input Pin I2C_ADDR0

(LSB). This transfer should be MSB first.

Send the read indicator bit (1).

10. Wait for the AD8191 to acknowledge the request.

11. The AD8191 serially transfers the data (eight bits) held in

the register indicated by the address set in Step 5. This data

is sent MSB first.

12. Acknowledge the data from the AD8191.

13. Perform one of the following:

13a. S

op condition (while holding the I2C_SCL

line high, pull the SDA line high) and release control

of the bus to end the transaction (shown in

end a st

13b.

ated start condition (while holding the

13c.

13d.

on (while holding the

Figure 30

Send a repe

I2C_SCL line high, pull the I2C_SDA line low) and

continue with Step 2 of the write procedure (previous

Write Procedure section) to perform a write.

Send a repeated start condition (while holding the

I2C_SCL line high, pull the I2C_SDA line low) and

continue with Step 2 of this procedure to perform a

read from another address.

Send a repeated start conditi

I2C_SCL line high, pull the I2C_SDA line low) and

continue with Step 8 of this procedure to perform a

read from the same address.

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