TMPR4937 datasheet(411/552 Pages) TOSHIBA

411 / 552 page

Chapter 14 AC-link Controller

14-5

14.3.3 Usage Flow

This section outlines a process flow when using the AC’97 connected to ACLC. Refer to the

subsequent sections for the details of each operation performed in this process flow. The diagrams

below describe the audio playback and recording processes. The modem transmission and reception

can be done in a similar way.

(*) Register settings such as volume can be made during data playback.

Figure 14.3.3 Audio Playback Process Flow

Start up AC-link

Enable ENLINK

Check AC’97 status

Setup DMA buffer

Configure DMAC

Start DMA Channel and

enable transmit-data DMA

Deassert ACRESET*

CODECRDY Interrupt

Start BITCLK

Set CODEC Ready

DAC Ready response

Set volume, etc.

Start transmit-data DMA

Start sending data to slot

DMAC generates Transfer

Completion interrupt (repeatedly)

Write to DMA buffer and update

DMA descriptor (repeatedly)

Stop updating DMA descriptor

DMAC channel goes inactive

DMA underrun error occurs

Stop transmit-data DMA

Stop sending data to slot

Check completion status

Disable transmit-data DMA

Dummy write to data register to

clear pending DMA request if any

Disable ENLINK

Assert ACRESET*

Stop BITCLK

Stop AC-link

Start audio playback

Stop audio playback

System Software

ACLC and DMAC

AC’97

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