
AD8196
Rev. 0 | Page 14 of 24
SERIAL CONTROL INTERFACE
RESET
On initial power-up, or at any point in operation, the AD8196
register set can be restored to the default values by pulling the
RESET pin to low according to the specification in
Table 1.
During normal operation, however, the RESET pin must be
pulled up to 3.3 V. Pulling the RESET pin to low sets the
HS_CH register to 0 (Input A) and incurs the associated
switching delay before the input can be switched to Input B,
regardless of the previous state of the AD8196.
WRITE PROCEDURE
To write data to the AD8196 register set, an I2C master (such as
a microcontroller) needs to send the appropriate control signals
to the AD8196 slave device. The signals are controlled by the
I2C master, unless otherwise specified. For a diagram of the
procedure, see
Figure 29. The steps for a write 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 AD8196 part address (seven bits). The upper six
bits of the AD8196 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 AD8196 to acknowledge the request.
5.
Send the register address (eight bits) to which data is to be
written. This transfer should be MSB first.
6.
Wait for the AD8196 to acknowledge the request.
7.
Send the data (eight bits) to be written to the register
whose address was set
in Step 5. This transfer should be
MSB first.
8.
Wait for the AD8196 to acknowledge the request.
9.
Do one of the following:
a.
Send a stop condition (while holding the I2C_SCL
line high, pull the I2C_SDA line high) and release
control of the bus to end the transaction (shown in
b.
Send a repeated start condition (while holding the
I2C_SCL line high, pull the I2C_SDA line low) and
another write.
c.
Send a repeated start condition (while holding the
I2C_SCL line high, pull the I2C_SDA line low) and
continue wit
h Step 2 of the read procedure (in the
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 the read procedure (in the
R/W
ACK
ADDR
START
FIXED ADDR PART
REGISTER ADDR
DATA
STOP
ACK
1
2
3
4
5
6
7
8
9
I2C_SCL
GENERAL CASE
I2C_SDA
EXAMPLE
I2C_SDA
*THE SWITCHING/UPDATE DELAY BEGINS AT THE FALLING EDGE OF THE
LAST DATA BIT; FOR EXAMPLE, THE FALLING EDGE JUST BEFORE STEP 8.
*
06
47
0-
0
29
Figure 29. I2C Write Procedure