Serial audio interface (SAI)
RM0090
948/1731
DocID018909 Rev 11
29.17.3 SAI
xFrame
configuration register (SAI_XFRCR) where x is A or B
Address offset: Block A: 0x00C
Address offset: Block B: 0x02C
Reset value: 0x0000 0007
Note:
This register has no meaning in AC’97 audio protocol
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
FSOFF FSPOL FSDEF
rw rw
r
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Res.
FSALL[6:0]
FRL[7:0]
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
Bits 31:19 Reserved, always read as 0.
Bit 18
FSOFF
: Frame synchronization offset. This bit is set and cleared by software.
0: FS is asserted on the first bit of the slot 0.
1: FS is asserted one bit before the first bit of the slot 0.
This bit has no meaning and is not used in AC’97 audio block configuration.
This bit must be configured when the audio block is disabled.
Bit 17
FSPOL
: Frame synchronization polarity. This bit is set and cleared by software
0: FS is active low (falling edge)
1: FS is active high (rising edge)
This bit is used to configure the level of the start of frame on the FS signal.
This bit has no meaning and is not used in AC’97 audio block configuration.
This bit must be configured when the audio block is disabled.
Bit 16
FSDEF
: Frame synchronization definition. This bit is set and cleared by software.
0: FS signal is a start frame signal
1: FS signal is a start of frame channel side identification
When the bit is set, the number of slots defined in the SAI_ASLOTR register has to be even. It
means that there will be half of this number of slots dedicated for the left channel and the other slots
for the right channel (e.g: this bit has to be set for I2S or MSB/LSB-justified protocols...)
This bit has no meaning and is not used in AC’97 audio block configuration.
This bit must be configured when the audio block is disabled.