CHAPTER 15 AUDIO INTERFACE UNIT (AIU)
User’s Manual U14272EJ3V0UM
316
15.3.2 Input (microphone)
1. Set conversion rate (0x0B00 017E: MCNVC(15:0) = any value)
2. Set D/A converter Vref setup time (0x0B00 0164: any value to be DVAREF(15:0)/PCLK frequency = 5
µ
s)
3. Enable DMA after setting DMA address in DCU
4. Set A/D converter’s Vref to ON (0x0B00 0172: ADENAIU = 1)
Microphone power can be set ON and microphone operation can be enabled (AIUMEN = 1) without waiting
for Vref resistor stabilization time (about 5
µ
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) (
µ
s)
5. Set microphone power ON via GPIO.
6. Enable microphone operation (0x0B00 017A: AIUMEN = 1)
Output A/D request to A/D converter
Acknowledge and 10-bit conversion data are returned from A/D converter.
Store data in MIDATREG.
0x0B00 0178: MDMAV = 0, MIDATV = 1
Transfer data from MIDATREG to MDMADATREG.
MDMAV = 1, MIDATV = 0
MSTINTR = 1 and an interrupt request (receive complete) occurs.
Issue DMA request and store MDMADATREG data to memory.
MDMAV = 0, MIDATV = 0
Issue an A/D request once per conversion timing interval and receive 10-bit data (becomes MIDLEINTR = 1
when DMA delays and MIDATV = 1 during conversion timing interval, and (data loss) interrupt request
occurs)
DMA page boundary interrupt request occurs at page boundary
Clear the page interrupt request to continue output.
7. Disable microphone operation (0x0B00 017A: AIUMEN = 0)
8. Set microphone power OFF via GPIO.
9. Set A/D converter’s Vref to OFF (0x0B00 0172: ADENAIU = 0)
10. Disable DMA in DCU
Figure 15-2. AUDIOIN Pin and Microphone Operation
AUDIOIN
sampling
<1> to <3> <4> <5><6>
<7> <8> <9> <10>
time
Содержание VR4181 mPD30181
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