XE3005 ETC, XE3005 Datasheet - Page 12

• Manufacturer Part Number: XE3005
• Description: (XE3005 / XE3006) Low-Power Audio CODEC
• Manufacturer: ETC

3 Serial Communications
3.1 Serial Audio Interface
The Serial Audio Interface is a 4-wire interface for bi-directional communication of audio data. The 4 terminals are
listed below:
The same clock (BCLK) and synchronization (FSYNC) signals are used for both sending and receiving. The
synchronization signal FSYNC must have a fixed ratio with the master clock signal MCLK.
The Serial Audio Interface supports two formats that are commonly used for audio/voice CODECs and that are
referred to as SFS (Short Frame Synchronization) and LFS (Long Frame Synchronization). Data can be
transmitted and received in 2 channels. Which channel is selected depends on the programmed values in the
registers. The two interface protocols are shown below.
SDI Data should be changed on the rising edge of BCLK. The SDI data will be read by the CODEC on the falling
edge of BLCK. SDO data will change on the rising edge of the BCLK. The SDO data should be read on the falling
edge of the BLCK. Each rising edge of the FSYNC indicates the start of a new sample.
12
FSYNC
FSYNC
BCLK
BCLK
SDO
SDO
SDI
SDI
BCLK:
FSYNC:
SDI:
SDO:
msb
msb
n
n
n
n
the FSYNC corresponds to the sample frequency of the CODEC.
15
15
Frame Synchronization. This signal indicates the start of a data word. The frequency of
Serial Data In, data received from external device and sent to DAC.
Serial Data Out, data received from ADC and sent to external device.
Bit serial clock, one clock cycle corresponds to one data bit transmitted or received.
15
15
Figure 13: Audio interface timing in SFS mode, channel 1
Figure 12: Audio interface timing LFS mode, channel 1
n
n
n
n
channel 1, sample n
14
14
channel 1, sample n
14
14
lsb
n
n
lsb
n
n
0
0
0
0
-
-
-
-
-
-
-
-
channel 2, sample n
channel 2, no data
-
-
-
-
Data Sheet
XE3005/XE3006
msb
n+1
msb
channel 1, sample n+1
n+1
n+1
channel 1, sample n+1
n+1
15
15
15
15
D0212-116