LM4560 datasheet(39/54 Pages) NSC

39 / 54 page

4.0 Functional Description (Continued)

will generate an interrupt and wait for next command.

•

Continuous DMA Mode

SB ESP is programmed to make continuous transfer to/

from CODEC. After each transfer of a specified block

size, the SB ESP will generate an interrupt and continue

the next transfer of the same block size after the interrupt

is acknowledged.

There are two ways to terminate continuous DMA mode

transfer.

Program the SB ESP to switch to normal DMA mode

transfer. At the end of the current DMA transfer, the SB

ESP will exit from continuous DMA mode and continue to

transfer using the specified normal DMA mode.

Send the exit continuous command. The SB ESP will exit

continuous DMA mode at the end of current block and

terminate the transfer.

•

Special DMA Mode

Once SB ESP is in the special DMA mode, it will not ac-

cept any further commands or data until the DMA mode is

terminated by the following two methods:

Non-continuous special DMA mode will exit special DMA

mode automatically at the end of transfer.

For continuous special DMA mode, a SB ESP_Reset() is

needed to exit special DMA mode. The SB ESP_Reset()

will only stop special DMA transfer, all other parameters

remain the same.

4.2.1.3 Legacy Sound Blaster Compatible Digitized Sound Sampling Rate Setup

4.2.1.3.1

4.2.1.3.2 Set Sampling Rate By Time Constant

Time constant = 256d − (1,000,000d / (channel * sampling rate))

4.2.1.3.3 Set Sampling Rate By Sampling Frequency

Frequency = 4 kHz to 48 kHz, either mono or stereo

4.2.1.4 Legacy Sound Blaster Esp Engine Digital Audio Command Set

0xh Reserved

1xh Set Audio Output Mode for 8 Bit Playback

2xh Set Audio Input Mode for 8 Bit Recording

3xh Reserved

4xh Set Sample Rate and Continuos/Special DMA Block Length

5xh Reserved

6xh Reserved

7xh SB ADPCM Playback

8xh Output Silence

9xh 8 Bit Special DMA Mode Playback/Record

Axh Reserved

Bxh 16-Bit DMA Audio I/O

Cxh 8-Bit DMA Audio I/O

Dxh Control DMA and Speaker

Exh SB ESP Version and Diagnostic Test

Fxh SB ESP Test

All 8-bit SB ESP command is unsigned PCM playback/recording command except Cxh command.

All 8-bit SB ESP command is mono playback/recording command except command 14h, 1Ch , 9xh and Cxh

4.2.1.5 8-Bit Playback Only Command 1Xh

SB ESP uses SBMX0E.1 to do mono/stereo playback.

SBMX0E.1 = 0 for mono playback

1 for stereo playback

4.2.1.5.1 Command Bit Definition

Bit 30 Direct or Normal DMA Mode

1 Continuous DMA Mode

Bit 20 Direct Mode

1 DMA Mode

Bit 10 8-Bit Data PCM

1 Reserved

Bit 00 Normal

LM4560 数据表(PDF) 39 Page - National Semiconductor (TI)

LM4560 数据表(HTML) 39 Page - National Semiconductor (TI)

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