![AKM AsahiKASEI AK4675 Скачать руководство пользователя страница 60](http://html1.mh-extra.com/html/akm/asahikasei-ak4675/asahikasei-ak4675_manual_2886255060.webp)
[AK4675]
MS0963-E-00
2008/05
- 60 -
ミ
Audio Interface Format
Four types of data formats are available and are selected by setting the DIF1-0 bits (
). 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. LRCK and
BICK are output from the AK4675 in master mode, but must be input to the AK4675 in slave mode.
Mode
DIF1 bit
DIF0 bit
SDTO (ADC)
SDTI (DAC)
BICK
Figure
0
0
0
DSP Mode
DSP Mode
≥
32fs
1
0
1
MSB justified
LSB justified
≥
32fs
2
1
0
MSB justified
MSB justified
≥
32fs
(default)
3 1
1
I
2
S compatible
I
2
S compatible
≥
32fs
Table 16. Audio Interface Format
In modes 1-3, the SDTO is clocked out on the falling edge (“
↓
”) of BICK and the SDTI is latched on the rising edge (“
↑
”).
In Modes 0 (DSP mode), the audio I/F timing is changed by BCKP and MSBS bits (
).
DIF1
DIF0
MSBS
BCKP
Audio Interface Format
Figure
0 0
MSB of SDTO is output by the rising edge (“
↑
”) of the
first BICK after the rising edge (“
↑
”) of LRCK.
MSB of SDTI is latched by the falling edge (“
↓
”) of the
BICK just after the output timing of SDTO’s MSB.
(default)
0 1
MSB of SDTO is output by the falling edge (“
↓
”) of the
first BICK after the rising edge (“
↑
”) of LRCK.
MSB of SDTI is latched by the rising edge (“
↑
”) of the
BICK just after the output timing of SDTO’s MSB.
1 0
MSB of SDTO is output by next rising edge (“
↑
”) of the
falling edge (“
↓
”) of the first BICK after the rising edge
(“
↑
”) of LRCK.
MSB of SDTI is latched by the falling edge (“
↓
”) of the
BICK just after the output timing of SDTO’s MSB.
0 0
1 1
MSB of SDTO is output by next falling edge (“
↓
”) of the
rising edge (“
↑
”) of the first BICK after the rising edge
(“
↑
”) of LRCK.
MSB of SDTI is latched by the rising edge (“
↑
”) of the
BICK just after the output timing of SDTO’s MSB.
Table 17. Audio Interface Format in Mode 0
If 16-bit data that ADC outputs 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.