AD8197ASTZ datasheet(17/32 Pages) AD

17 / 32 page

Preliminary Data Sheet

AD8197

PrA | 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 AD8197 register set, an I2C master (such

as a microcontroller) needs to send the appropriate control

signals to the AD8197 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 AD8197 part address (seven bits). The upper four

bits of the AD8197 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 AD8197 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 AD8197 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 AD8197 part address (seven bits) from Step 2.

The upper four bits of the AD8197 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 AD8197 to acknowledge the request.

11. The AD8197 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 AD8197.

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

Send a repeated start condition (while holding the

I2C_SCL lin

end a st

of the bus to end the transaction (shown in Figure 30).

13b.

e high, pull the I2C_SDA line low) and

ntinue

ious

13c.

13d.

2C_SDA line low) and

ntinue

SWITCH

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

t state change takes

ow;

with Step 2 of the write procedure (prev

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 condition (while holding the

I2C_SCL line high, pull the I

with Step 8 of this procedure to perform a

read from the same address.

ING/UPDATE DELAY

tion registers of the AD8197 and when tha

physical effect. This update delay occurs regardless of whether

the user programs the AD8197 via the serial or the parallel

control interface. When using the serial control interface, the

update delay begins at the falling edge of I2C_SCL for the last

data bit transferred, as shown in Figure 29. When using the

parallel control interface, the update delay begins at the

transition edge of the relevant parallel interface pin. This updat

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 AD8197 does not physically

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

new values during the delay window does not reset the wind

new values supersede the previously written values. At the en

of the delay window, the AD8197 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 AD8197 immediately updates and a new

delay window begins.

AD8197ASTZ Datasheet(PDF) 17 Page - Analog Devices

AD8197ASTZ Datasheet(HTML) 17 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Datasheet Download

Link URL