21 I
2
S
21-14
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
When BCLKPOL is 0, the I2S_SDO output changes at the falling edge of the I2S_SCLK clock (bit
clock) and the external DAC samples the data bit at the rising edge of I2S_SCLK.
When BCLKPOL is set to 1, the I2S_SDO output changes at the rising edge of I2S_SCLK and the ex-
ternal DAC samples the data bit at the falling edge of I2S_SCLK.
I2S_SCLK
I2S_SDO
BCLKPOL = 0 (default)
Data is shifted at the falling edge.
The external DAC samples the data at the rising edge.
I2S_SCLK
I2S_SDO
BCLKPOL = 1
Data is shifted at the rising edge.
The external DAC samples the data at the falling edge.
7.3 Bit Clock Polarity
Figure 21.
D5
DTFORM: I
2
S Output Data Format Select Bit
Selects either MSB first or LSB first as the data output direction.
1 (R/W): LSB first
0 (R/W): MSB first (default)
I2S_WS
I2S_SCLK
I2S_SDO
DTFORM = 0 (default)
I2S_WS
I2S_SCLK
I2S_SDO
DTFORM = 1
D0
D15
D2
D1
D0
D15 D14
D2
D1
D14
D0
D15
D0
D13 D14 D15
D0
D1
D13 D14
D1
D15
7.4 Output Data Format (Example in I
Figure 21.
2
S Mode)
D4
I2SOUTEN: I
2
S Output Enable Bit
Enables/disables output of the I
2
S signals.
1 (R/W): Enable (on)
0 (R/W): Disable (off) (default)
When I2SOUTEN = 0, the I2S_MCLK pin is maintained at standby status and the I2S_WS pin is fixed
at 0. The I2S_SDO pin is left unchanged. The I2S_SCLK pin is fixed at 0 (when BCLKPOL = 0) or 1
(when BCLKPOL = 1).
When I2SOUTEN is set to 1, all output pins enter standby status.
I2SOUTEN can be altered even if data is being output. This enables the I
2
S module to pause or resume
shifting data (data output).
D[3:2]
DTTMG[1:0]: I
2
S Output Data Timing Select Bits
Selects the data bit output timing.
7.2 Data Output Timing
Table 21.
DTTMG[1:0]
Data output timing mode
0x3
Reserved
0x2
Right justified mode
0x1
Left justified mode
0x0
I
2
S mode
(Default: 0x0)