[AK4634]
■ Audio Interface Format
Four types of data formats are available and are selected by setting the DIF1-0 bits. (Table 16) In all modes, the serial data
is MSB first, 2’s complement format. Audio interface formats can be used in both master and slave modes. FCK and
BICK are output from the AK4634 in master mode, but must be input to the AK4634 in slave mode.
In Mode 1-3, the SDTO is clocked out on the falling edge of BICK and the SDTI is latched on the rising edge.
Mode
DIF1
DIF0
SDTO (ADC)
DSP Mode
SDTI (DAC)
DSP Mode
MSB justified
MSB justified
BICK
≥ 16fs
≥ 32fs
≥ 32fs
≥ 32fs
Figure
See Table 17
Figure 25
Figure 26
Figure 27
0
1
2
3
0
0
1
1
0
1
0
1
MSB justified
MSB justified
(default)
I2S compatible I2S compatible
Table 16. Audio Interface Format
In Mode0 (DSP mode), the audio I/F timing is changed by BCKP and MSBS bits.
When BCKP bit is “0”, SDTO data is output by rising edge of BICK, SDTI data is latched by falling edge of BICK.
When BCKP bit is “1”, SDTO data is output by falling edge of BICK, SDTI data is latched by rising edge of BICK.
MSB data position of SDTO and SDTI can be shifted by MSBS bit. The shifted period is a half of BICK.
MSBS bit BCKP bit
Audio Interface Format
Figure 28
0
0
1
1
0
1
0
1
(default)
Figure 29
Figure 30
Figure 31
Table 17. Audio Interface Format in Mode 0
If 16-bit data, the output of ADC, is converted to 8-bit data by removing LSB 8-bit, “−1” at 16bit data is converted to “−1”
at 8-bit data. And when the DAC playbacks this 8-bit data, “−1” at 8-bit data will be converted to “−256” at 16-bit data
and this is a large offset. This offset can be removed by adding the offset of “128” to 16-bit data before converting to 8-bit
data.
FCK
0
1
2
3
8
9
10 11
12
13 14
15
0
1
2
3
8
9
10 11
12
13 14
15
0
1
BICK(32fs)
SDTO(o)
15 14
8
7
7
6
6
5
4
4
3
3
2
1
1
0
0
15
15
13
SDTI(i)
15 14
5
2
13
Don’t Care
0
1
2
3
14
15 16
17
18
31
0
1
2
3
14
15 16
17
18
31
0
1
BICK(64fs)
SDTO(o)
15 14 13
2
1
0
15
Don’t Care
15:MSB, 0:LSB
15 14
1
0
Don’t Care
SDTI(i)
Data
1/fs
Figure 25. Mode 1 Timing
Rev. 0.5
2007/10
- 31 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
