21 I
2
S
21-6
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
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 D14
D15 D14
18
17
D2
D3
D1
D0
4.7 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 starts 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
4.8 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 is 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
4.9 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].
Data Output Control
21.5
The following shows audio data output procedure:
1. Set up the I
2
S conditions as described in the previous section.
2. Set up the interrupt or DMA conditions as described in Section 21.6.
3. Set the output channel mode using CHMD[1:0]/I2S_CTL register.
5.1 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.