Serial audio interface
5 Serial audio interface
STA350B, STA350BW
The STA350Bx audio serial input interface has been designed to interface with standard digital audio components and to accept a number of serial data formats. The STA350Bx always acts as the slave when receiving audio input from standard digital audio components. Serial data for two channels is provided using three inputs: left/right clock
LRCKI, serial clock BICKI, and serial data SDI12.
The SAI bit and the SAIFB bit are used to specify the serial data format. The default serial data format is I
2
S, MSB-first.
5.0.1 Timings
In the STA350Bx the BICKI and LRCKI pins are configured as inputs and they must be supplied by the external peripheral.
Figure 18. Timing diagram for SAI interface t
BCH t
BCL
80%
BICKI 40% t
BCy
LRCKI
SDI12 t
LRH t
LRSU
5.0.2
5.0.3
Symbol t
BCy t
BCH t
BCL t
LRSU t
LRH t
LRJT
Table 7. Timing parameters for slave mode
Parameter
BICK cycle time
BICK pulse width high
BICK pulse width low
LRCKI setup time to BICKI strobing edge
LRCKI hold time to BICKI strobing edge
LRCKI jitter tolerance
Min.
Typ.
Max.
Unit
80
40
40
40
40
-
-
-
-
-
-
-
40
-
-
ns ns ns ns ns ns
Delay serial clock enable
To tolerate anomalies in some I
2
S master devices, a PLL clock cycle delay can be added to the BICKI signal before the SAI interface.
Channel input mapping
Each channel received via I
2
S can be mapped to any internal processing channel via the channel input mapping registers. This allows for flexibility in processing. The default settings of these registers map each I
2
S input channel to its corresponding processing channel.
28/94 DocID018572 Rev 7
