at85c51snd3b ATMEL Corporation, at85c51snd3b Datasheet - Page 153

• Manufacturer Part Number: at85c51snd3b
• Description: Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

Mixing Mode
Signal Clipping
Interrupts
7632C–MP3–11/06
A mixing mode can be established by setting MIXEN bit in AUCON. It consists in mixing
the ADC output coming from microphone or line-in inputs with the output coming from
the audio processor before feeding the internal or external audio DAC.
When volume controls (global + equalizer + bass boost) leads to signal saturation, out-
put signal is clipped and ACLIPI flag is set in APINT. In such case, strategy to reduce
volume is under user’s firmware responsibility. ACLIPI flag can generate an interrupt by
setting ACLIPE bit in APIEN.
As shown in Figure 73, the audio processor interrupt request is generated by 8 different
sources: the APREQI, APRDYI, ACLIPI and APGPI4:0 flags in APINT. Both sources
can be enabled separately by using the APREQE, APRDYE, ACLIPE and APGPE4:0
bits in APIEN. A global enable of the audio processor interrupt is provided by setting the
EAUP bit in IEN0 register.
The interrupt is requested each time one of the sources is asserted.
Figure 73. Audio Processor Interrupt System
APGPI3:0
APREQI
APRDYI
APEVTI
APINT.7:4
ACLIPI
APINT.0
APINT.1
APINT.2
APINT.3
APGPE3:0
APREQE
APRDYE
APEVTE
ACLIPE
APIEN.7:4
APIEN.0
APIEN.1
APIEN.2
APIEN.3
AT85C51SND3B
EAUP
IEN0.6
Audio
Processor
Interrupt
Request
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