VR4102 datasheet(422/701 Pages) NEC

422 / 701 page

CHAPTER 20 AIU (AUDIO INTERFACE UNIT)

422

20.3.2 Input (MIC)

Set conversion rate (0x0B00 0174: MCNVR = arbitrary)

Set input data area in DMAAU

DMA enable in DCU

Set A/D converter’s Vref to ON (0x0B00 0172: ADENAIU = 1)

MIC power can be set ON and MIC operation can be enabled without waiting for Vref resistor

stabilization time (about 5

Ps). 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) (

Ps)

Set MIC power ON via GPIO.

MIC operation enable (0x0B00 017A: AIUMEN = 1)

Output A/D request (ADREQAIU) to A/D converter

Return acknowledge (aiuadack) and 10-bit conversion data from A/D converter

Store data in MIDATREG

0x0B00 0178: MDMAV = 0, MIDATV = 1

Transfer data from MIDATREG to MDMADATREG

MDMAV = 1, MIDATV = 0

The INTMST value becomes “1” and an interrupt (receive complete) occurs

Issue DMA request and store MIDMADATREG data to memory.

MDMAV = 0, MIDATV = 0

An A/D request is issued once per conversion timing interval and 10-bit data is received (becomes

MIDLEINTR = 1 when DMA is slow and MIDATV = 1 during conversion timing interval, and (data loss)

interrupt occurs)

DMA page boundary interrupt occurs at page boundary

(Page interrupt is cleared when output continues)

MIC operation to disable (0x0B00 017A: AIUMEN = 0)

Set MIC power OFF via GPIO

Set A/D converter’s Vref to OFF (0x0B00 0172: AIUADEN = 0)

10. DMA disable in DCU

VR4102 Datasheet(PDF) 422 Page - NEC