CHAPTER 15 AUDIO INTERFACE UNIT (AIU)
User’s Manual U14272EJ3V0UM
315
15.3 Operation Sequence
15.3.1 Output (speaker)
1. Set conversion rate (0x0B00 016E: SCNVC(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 D/A converter’s Vref to ON (0x0B00 0168: DAENAIU = 1)
5. Wait for Vref resistor stabilization time (about 5
µ
s) (use the RTC counter)
Even if speaker power is set to ON and speaker operation is enabled (AIUSEN = 1) without waiting for Vref
resistor stabilization time, speaker output starts after the period calculated with the formula below.
5 + 1/conversion rate (44.1, 22.05, 11.025, or 8) (
µ
s)
In this case, however, a noise may occur when speaker power is set to ON.
6. Set speaker power ON via GPIO.
7. Enable speaker operation (0x0B00 017A: AIUSEN = 1)
DMA request
Receive acknowledge and DMA data from DMA
0x0B00 0178: SDMAV = SODATV = 1
Output 10-bit data (0x0B00 0166: SODAT(9:0)) to D/A converter
SODATV = 0, SDMAV = 1
Send SDMADATREG data to SODATREG.
SODATV = 1, SDMAV = 0
Output DMA request and store the data after the next into SDMADATREG.
SODATV = 1, SDMAV = 1
Update data at each conversion timing interval (becomes SIDLEINTR = 1 when DMA delays and SODATV =
0 during conversion timing interval, and (mute) interrupt request occurs)
DMA page boundary interrupt request occurs at page boundary
Clear the page interrupt request to continue output.
8. Disable speaker operation (0x0B00 017A: AIUSEN = 0)
9. Set speaker power OFF via GPIO.
10. Set D/A converter’s Vref to OFF (0x0B00 0168: DAENAIU = 0)
11. Disable DMA in DCU
Figure 15-1. Speaker Output and AUDIOOUT Pin
AUDIOOUT
V
DD
/2
time
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