21 I
2
S
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
21-15
When DTTMG[1:0] is set to 0x0 (default), I
2
S mode is selected. In this mode, the first bit of each data
is output after one I2S_SCLK clock delay from the I2S_WS signal edge.
1
2
3
14
15
16
1
2
3
I2S_WS
I2S_SCLK
Bit clock cycle count
(by setting WSCLKCYC[4:0])
I2S_SDO
(L channel)
(R channel)
(MSB first, number of bit clock cycles = 18)
D15
D2
D3
D1
D0
D14
D15 D14
18
17
7.5 Data Output Timing 1 (I
Figure 21.
2
S Mode)
When DTTMG[1:0] is set to 0x1, left justified mode is selected. In this mode, each data output will
start at the I2S_WS signal edge.
1
2
3
14
15
16
1
2
3
I2S_WS
I2S_SCLK
Bit clock cycle count
(by setting WSCLKCYC[4:0])
I2S_SDO
(L channel)
(R channel)
D15
D2
D1
D0
D14 D13
D15 D14 D13
(MSB first, number of bit clock cycles = 18)
18
17
7.6 Data Output Timing 2 (Left Justified Mode)
Figure 21.
When DTTMG[1:0] is set to 0x2, right justified mode is selected. In this mode, output data will be right
justified to the I2S_WS signal edge.
1
2
3
4
5
16
18
17
1
2
3
4
5
I2S_WS
I2S_SCLK
Bit clock cycle count
(by setting WSCLKCYC[4:0])
I2S_SDO
(L channel)
(R channel)
(MSB first, number of bit clock cycles = 18)
D15
D2
D1
D0
D0
D14 D13
D15 D14 D13
0 or D15
0 or D15
7.7 Data Output Timing 3 (Right Justified Mode)
Figure 21.
Note: When using right justified mode, the number of bit clock cycles (sample clock period) must be
equal to or greater than [Data bit size + 2].
D[1:0]
CHMD[1:0]: I
2
S Output Channel Mode Select Bits
Selects the I
2
S output channel mode.
7.3 Output Channel Mode Selection
Table 21.
CHMD[1:0]
Output channel mode
L channel
R channel
0x3
Mute
0
0
0x2
Mono (L)
Data output
0
0x1
Mono (R)
0
Data output
0x0
Stereo
Data output
Data output
(Default: 0x0)
The output channel mode can be switched even if data is being output. In this case, the mode changes
after the current word output has finished.
When mute mode is selected, the I2S_SDO pin is fixed at 0. However, the FIFO and shift register run
the same as stereo mode and three clock signals are output normally. Also in mono mode, the I2S_SDO
pin is fixed at 0 during the output period for the unselected channel.
The FIFO data is read out normally, therefore an interrupt occurs.