LM4560 datasheet(18/54 Pages) NSC

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3.0 Register Description (Continued)

When MPU-401 MIDI engine is at internal loopback opera-

tion state (MPUR3.7 is set 1), MPUR1.7 is masked from

MIDI-IN FIFO state automatically. This means if MIDI-IN

FIFO is not empty, MPUR1.7 is still reading as 1. When

MIDI-IN FIFO is full, MIDI clock will be stopped until MIDI-IN

FIFO is not full.

3.4.4 Legacy Gameport Register

These 16-byte registers can be accessed on Audio Base (I/O

or MEM), or Gameport Base.

3.4.4.1 GAMER0 (Gameport Control Register)

Address: AudioBase + 30h

Size:

2 bits

Type:

Read/Write

Default:

Bit 7

0 Disable Enhanced Digital Gameport;

1 Enable Enhanced Digital Gameport;

Bit 6

0 Disable Testmode for Enhanced Mode Gameport

1 Enable Testmode for Enhanced Mode Gameport

Bit 5..0 X Reserved;

When Bit 6 is set, the gamecounter will overflow every 1024

AC97 Bitclk. Bit 6 is only useful when Bit 7 is set. Bit 7 will be

automatically cleared if there are any I/O operation to

GAMER1.

3.4.4.2 GAMER1 (Legacy Gameport I/O Register)

Address: AudioBase + 31h or GAMEBase+0-7h

Size:

8 bits

Type:

Read/Write

Default:

00h

Write

Bit 7..0

Trigger the Legacy Gameport I/O

Read Cycle

Read

Bit 7

Joystick B Button 1 Pressed (Input

Pad Stay at Low Level);

Joystick B Button 1 Released (Input

Pad Stay at High Level);

Bit 6

Joystick B Button 0 Pressed (Input

Pad Stay at Low Level);

Joystick B Button 0 Released (Input

Pad Stay at High Level);

Bit 5

Joystick A Button 1 Pressed (Input

Pad Stay at Low Level);

Joystick A Button 1 Released (Input

Pad Stay at High Level);

Bit 4

Joystick A Button 0 Pressed (Input

Pad Stay at Low Level);

Joystick A Button 0 Released (Input

Pad Stay at High Level);

Bit 3

Joystick B Y-Axies Input Pad Stay at

High Level

Joystick B Y-Axies Input Pad Stay at

Low Level

Bit 2

Joystick B X-Axies Input Pad Stay at

High Level

Joystick B X-Axies Input Pad Stay at

Low Level

Bit 1

Joystick A Y-Axies Input Pad Stay at

High Level

Joystick A Y-Axies Input Pad Stay at

Low Level

Bit 0

Joystick A X-Axies Input Pad Stay at

High Level

Joystick A X-Axies Input Pad Stay at

Low Level

3.4.4.3 GAMER2 (Enhanced Gameport Position

Address: AudioBase + 34h

Size:

32 bits

Type:

Read Only

Default:

00000000h

Bit 31..16 Joystick A Y-Axies Position Latch Value (16 bit un-

signed)

Bit 15..0 Joystick A X-Axies Position Latch Value (16 bit un-

signed)

3.4.4.4 GAMER3 (Enhanced Gameport Position

Address: AudioBase + 38h

Size:

32 bits

Type:

Read Only

Default:

00000000h

Bit 31..16 Joystick B Y-Axies Position Latch Value (16 bit un-

signed)

Bit 15..0 Joystick B X-Axies Position Latch Value (16 bit un-

signed)

3.4.4.5 Implementation Note

Any I/O operation to legacy GAMEBase will function as nor-

mal

gameport

mode.

enhanced

gameport

mode

(GAMER0.7 is set 1), when the 16 bit game counter over-

flowed, the external pad for joystick A&B X-Y Axies State will

stop drived low, then game counter will counting up from

zero with AC97 bitclock (12.288 MHz ). Each game position

latch (4 * 16 bits) will store the game counter value when its

corresponding axies state pad recharged from low to high.

When the game counter overflowed, the game position latch

will be set to the overflowed value (0FFFFh) if its corre-

sponding axies state pad is still low.

The game position latches can be read in word or

double word format. These latches should be frozen

when reading and be freed after reading.

3.4.5 Serial Interface Control Register:

These 16-byte registers can only be accessed on Audio

Base (I/O or MEM).

3.4.5.1 ACWR (AC-97 Mixer Write Register)

Address: AudioBase + 40h

Size:

32 bits

Type:

Read/Write

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