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15.5.5 Interrupt control
Figure 15-9 shows interrupt control.
Interrupt source
Set 1 in INT_CLR/INT_STATUS
Interrupt request mask
(INT_MSK register)
15.5.6 SRC (sample rate converter)
This section explains the converter and filter functions.
Since the AC97U handles all audio I/O data by using 48 kHz samples, rate conversion must be performed for data
having various sample conditions. The converter function performs this rate conversion.
However, when a rate conversion is simply performed from PCM data, distortion occurs in the output analog
waveform. Therefore, the filter function is used to restore the waveform.
(1) Input data format
• 16-bit data
• Bit 15 is a sign bit
• When the sign bit is 1, set two's-complement data for the data part (bits 14 to 0).
• The decimal point position can be selected. However, the same position is set for all data (fixed decimal
point).
Bit number
Coefficient range when the decimal point position is A: −1 < X < 1
Remark
Coefficient range when the decimal point position is B: −32767 < X < 32767
CHAPTER 15 AC97U (AC97 UNIT)
Figure 15-9. Interrupt Control
FF
S
R
register
Figure 15-10. Input Data
15
14
13 12
11
10
Decimal point position A
Sign bit
User's Manual U14579EJ2V0UM
AND
Various types of interrupt requests
9
8
7
6
5
4
3
Decimal point position B
OR
INTR
2
1
0
383
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