21 I
2
S
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
21-1
I
21
2
S
I
21.1
2
S Module Overview
The S1C33L26 has a built-in I
2
S module that outputs PCM data in the I
2
S (Inter-IC Sound) format. An audio output
circuit can be simply configured by connecting external devices such as an audio DAC to the I
2
S bus.
The following shows the features of the I
2
S module:
• Operates as an I
2
S master device.
• Generates the bit clock, word-select clock, and master clock.
• Supports 16-bit PCM data resolution.
• A 16-byte transmit FIFO (16 bits
×
2 channels
×
4) is included.
• Stereo, mono (L and R), and mute modes are software selectable.
• FIFO data empty (half empty, whole empty, or one empty) can issue an interrupt request.
• FIFO one empty interrupt cause can invoke DMA.
• Clock polarity is software configurable.
• Data shift direction (MSB first/LSB first) is software selectable.
• Supports I
2
S mode, left justified mode, and right justified mode.
Figure 21.1.1 shows the configuration of the I
2
S module.
I2S_MCLK
I2S_SCLK
I2S_WS
I2S_SDO
PCLK1
(from CMU)
FIFO control
Internal bus
ITC, DMAC
I
2
S
Bus I/F
and
control
registers
Interrupt
control
Transmit FIFO
(16 bits
×
2 ch.
×
4)
Clock control
I
2
S interface
Shift register
1.1 I
Figure 21.
2
S Module Configuration
I
21.2
2
S Output Pins
Table 21.2.1 lists the I
2
S pins.
2.1 List of I
Table 21.
2
S Pins
Pin name
I/O
Qty
Function
I2S_SDO
O
1
I
2
S data output pin
Outputs serial PCM data.
I2S_WS
O
1
I
2
S word-select signal (LRCLK) output pin
Outputs the word-select signal that indicates the channel (L or R) of the data be-
ing output.
I2S_SCLK
O
1
I
2
S synchronous clock (bit clock) output pin
Outputs the synchronous clock (bit clock) for serial data.
I2S_MCLK
O
1
I
2
S master clock output pin
Outputs the I
2
S master clock.