LM4560 datasheet(38/54 Pages) NSC

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4.0 Functional Description (Continued)

Table CODEC Buffer Partitioning

4.1.10 Legacy Channel Playback/Recording

This function block is intended to emulate legacy DMA using PCI bus master engine.

All parameters used by this Legacy Channel are stored in register.

TABLE 1. LBL (Legacy Burst Length)

LBL CA[1:0]

SB_Data_type[2:1]=00

1112

SB_Data_type[2:1]=01

1222

SB_Data_type[2:1]=10

1222

SB_Data_type[2:1]=11

2333

TABLE 2. LBL1 (Legacy Burst Length)

LBL1 BA[1:0]

SB_Data_type[2:1]=00

1111

SB_Data_type[2:1]=01

1112

SB_Data_type[2:1]=10

1112

SB_Data_type[2:1]=11

1222

4.2 LEGACY AUDIO

The legacy Audio includes the SB Engine, OPL3 trapping, MPU-401 interface and Gameport.

4.2.1 SB Engine

4.2.1.1 Legacy SB ESP I/O Procedure

4.2.1.1.1 SB ESP Read Data Procedure

4.2.1.1.2 SB ESP Write Procedure

4.2.1.1.3 SB ESP Reset Procedure

4.2.1.1.4

4.2.1.1.5 Legacy SB Interrupt Acknowledge Procedure

4.2.1.2 Legacy Sound Blaster Compatible Digitized Sound Transfer Method

4.2.1.2.1 Direct Mode

SB ESP is programmed to do audio input/output on each command. All delay time is controlled by CPU delay loop or timer in-

terrupt. Only 8-bit mono input/output is supported.

Input:

a. ESP_Write(20h)

b. Next 8-bit mono PCM = ESP_Read()

c. Wait until next sample time, go to a.

4.2.1.2.2 DMA Mode

•

Normal DMA Mode

SB ESP is programmed to make one transfer with a

specified block size. At the end of transfer, the SB ESP

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