AT85C51SND3Bx
Mixing Mode
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.
Signal Clipping
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.
Interrupts
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
APREQI
APINT.0
APREQE
APIEN.0
APRDYI
APINT.1
APRDYE
APIEN.1
Audio
Processor
ACLIPI
APINT.2
Interrupt
Request
ACLIPE
EAUP
APIEN.2
IEN0.6
APEVTI
APINT.3
APEVTE
APIEN.3
APGPI3:0
APINT.7:4
APGPE3:0
APIEN.7:4
153
7632A–MP3–03/06
ATMEL [ ATMEL ]
