AD8190

Rev. 0 | Page 15 of 24

START

FIXED PART ADDR

REGISTER ADDR

FIXED PART ADDR

DATA

STOP

ACK

ADDR ACK

R/W

ADDR ACK

ACK

R/W

SR

1

2

3

4

5

6

7

8

9 10 11

12

13

I2C_SCL

GENERAL CASE

I2C_SDA

EXAMPLE

I2C_SDA

READ PROCEDURE

as a microcontroller) needs to send the appropriate control

signals to the AD8190 slave device. The signals are controlled

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

as follows:

1.

Send a start condition (while holding the I2C_SCL line

high, pull the I2C_SDA line low).

2.

Send the AD8190 part address (seven bits). The upper six

bits of the AD8190 part address are the static value

[100100] and the LSB is set by Input Pin I2C_ADDR. This

transfer should be MSB first.

3.

Send the write indicator bit (0).

4.

Wait for the AD8190 to acknowledge the request.

5.

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

be read. This transfer should be MSB first.

6.

Wait for the AD8190 to acknowledge the request.

7.

Send a repeated start condition (Sr) by holding the

I2C_SCL line high and pulling the I2C_SDA line low.

8.

Resend the AD8190 part address (seven bits) from Step 2.

The upper six bits of the AD8190 part address compose the

static value [100100]. The LSB is set by Input Pin I2C_ADDR.

This transfer should be MSB first.

9.

Send the read indicator bit (1).

10. Wait for the AD8190 to acknowledge the request.

11. The AD8190 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 AD8190.

13. Do one of the following:

a.

Send a stop 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 Figure 30).

b.

Send a repeated start condition (while holding the

I2C_SCL line high, pull the I2C_SDA line low) and

continue with Step 2 of the write procedure (see the

previous Write Procedure section) to perform a write.

c.

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.

d.

Send a repeated start condition (while holding the

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.

SWITCHING/UPDATE DELAY

There is a delay between when a user writes to the configura-

tion registers of the AD8190 and when that state change takes

physical effect. This update delay begins at the falling edge of

I2C_SCL for the last data bit transferred, as shown in Figure 29.

This update delay is register specific and the times are specified

in Table 1.

During a delay window, new values can be written to the

configuration registers but the AD8190 does not physically

update until the end of that register’s delay window. Writing

new values during the delay window does not reset the window;

new values supersede the previously written values. At the end

of the delay window, the AD8190 physically assumes the state

indicated by the last set of values written to the configuration

registers. If the configuration registers are written after the delay

window ends, the AD8190 immediately updates and a new

delay window begins.