
CHAPTER 10 AIU (AUDIO INTERFACE UNIT)
User’s Manual U14579EJ2V0UM
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10.3.2 Input (MIC)
<1> Set A/D conversion rate (MCNVR(2:0) area in MCNVRREG register = any value)
<2> Set input data area in DMAAU
<3> DMA enable in DCU
<4> Set A/D converter’s ADAVREFP to ON (ADENAIU bit of MCNTREG register = 1)
MIC power can be set ON and MIC operation can be enabled (AIUMEN bit = 1) without waiting for
ADAVREFP resistor stabilization time (about 5
s). However, in such a case, sampling starts after the
period calculated with the formula below.
5 + 1/conversion rate (44.1, 22.05, 11.025, or 8 ksps) (
s)
<5> Set MIC power to ON via GPIO.
<6> MIC operation enable (AIUMEN bit of SEQREG register = 1)
When the MIC operation is enabled, the following internal operations occur.
1. Output A/D conversion request to A/D converter
2. Return acknowledge and 12-bit conversion data from A/D converter.
3. Store data in MIDATREG register.
DVALIDREG register’s MDMAV bit = 0, MIDATV bit = 1
4. Transfer data from MIDATREG register to MDMADATREG register.
MDMAV bit = 1, MIDATV bit = 0
The INTMST bit becomes 1 and an interrupt (receive complete) occurs.
5. Issue DMA request and store MIDMADATREG register data to memory.
MDMAV bit = 0, MIDATV bit = 0
6. An A/D request is issued once per conversion timing interval and 12-bit data is received
Becomes MIDLEINTR bit = 1 when DMA is slow and MIDATV bit = 1 during conversion timing
interval, and (data loss) interrupt occurs
7. DMA page boundary interrupt occurs at page boundary
Clear the page interrupt request to continue output.
<7> MIC operation disable (AIUMEN bit of SEQREG register = 0)
<8> Set MIC power to OFF via GPIO.
<9> Set A/D converter’s ADAVREFP to OFF (ADENAIU bit of MCNTREG register = 0)
<10> DMA disable in DCU
Figure 10-2. AUDIOIN Pin and MIC Operation
AUDIOIN
Sampling
<1> to <3> <4> <5> <6>
<7> <8> <9><10>
Time