![](http://datasheet.mmic.net.cn/Analog-Devices-Inc/AD1970JSTZ_datasheet_95733/AD1970JSTZ_12.png)
AD1970
Rev. 0 | Page 12 of 20
CONTROL PORT
I2C PORT OVERVIEW
The AD1970 can be controlled using the I2C port. In general,
there are three parameters that can be controlled: the encoder
output level, the Phat Stereo image enhancement algorithm, and
the dialog enhancement algorithm. It is also possible to write
new data into the parameter RAM to alter the filter coefficients
used in the BTSC encoding process. Since this is a fairly
complex topic and is unnecessary for normal operation of the
chip, the details are not included in this data sheet; please
contact ADI sales if modifications to the BTSC filters are
required.
The I2C port uses a 2-wire interface consisting of SDA, the
bidirectional data line, and SCL, the clock.
The R/W bit is low for a write operation and high for a read
operation. The 10-bit address word is decoded into either a
location in the parameter RAM or one of the registers. The
number of data bytes varies according to the register or
memory being accessed. The detailed data format diagram for
continuous-mode operation is given in the section.
I2C ADDRESS DECODING
Table 16 shows the address decoding used in the I2C port. Four different addresses are available to avoid conflicting addresses
on an I2C bus. The I2C address space encompasses a set a
registers and the parameter RAM. The parameter RAM is
loaded on power-up from an on-board boot ROM.
Table 16. I2C Address Settings
ADR1
ADR0
I2C Address
0
0x20
0
1
0x21
1
0
0x22
1
0x23
Table 17. I2C Port Address Decoding
Register Address
Register Name
Read/Write Word Length
0
Input Level Control
Write: 22 bits
Read: 22 bits
1 to 254
Parameter RAM
255
Output Level Control
256
Control Register 1
Write: 11 bits
Read: 6 bits
257
Control Register 2
Write: 22 bits
258
ADC Volume Control
259
Stereo Spreading Control
260
Dialog Enhancement Control