CS4222_02 Datasheet, PDF (22/29 Pages) Cirrus Logic – 20-Bit Stereo Audio Codec with Volume Control

CS4222
4.6.2 I²C Mode
In I²C mode, SDA is a bidirectional data line. Data is clocked into and out of the part by the clock, SCL, with
the clock-to-data relationship as shown in Figure 12. There is no CS pin. Pin AD0 forms the partial chip ad-
dress and should be tied to VD or DGND as desired. The upper 6 bits of the 7 bit address field must be
001000. In order to communicate with the CS4222, the LSB of the chip address field (first byte sent to the
CS4222) should match the setting of the AD0 pin. The eighth bit of the address byte is the R/W bit (high for
a read, low for a write). If the operation is a write, the next byte is the Memory Address Pointer which selects
the register to be read or written. If the operation is a read, the contents of the register pointed to by the
Memory Address Pointer will be output. Setting the auto increment bit in MAP allows successive reads or
writes of consecutive registers. Each byte is separated by an acknowledge bit.
SDA
001000
ADDR
AD0
R/W
ACK
DATA 1-8
ACK
DATA 1-8
ACK
SCL
Start
Stop
Figure 12. Control Port Timing, I²C mode
4.6.3 Control Port Bit Definitions
All registers can be written and read in I²C mode, except the Converter Status Report Byte (#6) and the
CLKE and CALP bits in the ADC control byte (#1) which are read only. SPI mode only allows for register
writing (see the following bit definition tables for bit assignment information).
4.7 De-Emphasis
The CS4222 is capable of digital de-emphasis for 32, 44.1, or 48 kHz sample rates. Implementation of digital
de-emphasis requires reconfiguration of the digital filter to maintain the filter response at multiple sample rates
(see Figure 13).
De-emphasis control is achieved with the DEM1/0 pins or through the DEM2-0 bits in the DSP Port Mode Byte
(#2). The default state on power-up is de-emphasis controlled via the DEM1/0 pins (DEM2-0 bits=0). DEM1/0
pin control is defined in Table 4.
Table 4. De-Emphasis filter control
DEM 1
0
0
1
1
DEM 0
0
1
0
1
De-emphasis
32 kHz
44.1 kHz
48 kHz
OFF
Gain
dB
0 dB
T1 = 50 µs
-10 dB
T2 = 15 µs
F1
F2 Frequency
Figure 13. De-emphasis Curve.
22
DS236F1