RM0082
RS_Telecom IP
Doc ID 018672 Rev 1
779/844
Figure 99.
I2S data flow on 2*32 bit data
34.4.9 DAC
block
DAC block implements a noise shapter of order 2 based on the TDM hardware. DAC cell is
designed to work when not using the TDM. Its over sampling can be set between 32 and
256. DAC block uses samples placed in the buffer memory. Action memory informs if a new
sample need to be sent to the DAC during the next byte. Input data must be 32 bit wide,
either in 2’s complement or binary representation.
When used in conjunction with the TDM, a bufferization channel has to be reserved for the
DAC. In this case, the input sampling frequency must be either 8 kHz (standard TDM) or 16
kHz (when connecting wideband CODECs for instance). The number of bits in a frame must
be fixed between 32 and 256, leading to an over sampling factor of 32 to 256. For example,
an 8 kHz input and a 256 bit frame will generate a 204 kHz output.
Left
Left
Right
Right
Left
Left
Right
Right
I2S_LRCK
1 bit
I2S_DIN
I2S_LRCK
1 bit
I2S_DIN
By
te0
R
By
te1
R
By
te2
R
By
te3
R
By
te
0L
B
yte1L
By
te
2L
By
te
3L
By
te0
R
By
te1
R
By
te2
R
By
te3
R
By
te
0L
By
te1
L
By
te2
L
By
te3
L
0000
07FF
0800
0FFF
Input
Buffer
Output
Buffer
1000
1FFF
To and From
Processor
To and From
Processor
I2S_DOUT
By
te0
R
By
te1
R
By
te2
R
By
te3
R
B
yte0L
By
te1
L
B
yte2L
B
yte3L
B
yte0R
B
yte1R
B
yte2R
B
yte3R
B
yte0L
By
te
1L
By
te
2L
By
te
3L