YMF721 datasheet(10/41 Pages) LSI

10 / 41 page

YMF721

July 10, 1997

- 10 -

Notes:

´ : Don’t care

When address has been written into FM block, the time required to wait until writing of address

or data into Wavetable block is started is 0 (zero) nsec. When address has been written into

Wavetable block, the time required to wait until writing of address or data into FM block is

started is also 0 (zero) nsec. When FM block has been accessed, it is necessary to wait 860 nsec

or more before the FM block can be accessed again.

Interrupt

AIRQ

: Interrupt signal ("H" : Interrupt)

YMF721 (OPL4-ML2) is able to provide one interrupt signal. There are two types of sources of

this interrupt signal as follows.

1) Two timer flags that are used for tempo counter of FM synthesizer

2) The flag that occurs when internal processor writes data into the Command response register

The flags described in 2) is disabled as a default.

3. Serial audio interface

YMF721 (OPL4-ML2) can be connected directly with an external DAC such as YAC516 through BCO,

LRO, WCO and DO3-0 pins.

BCO...

Outputs bit clock. The frequency of this clock is 48 fs. (fs is the sampling

frequency that is equal to the frequency of clock outputted from LRO.) Typical

duty factor of this signal is 50 %.

LRO...

Specifies a channel for serial audio data. When LRO is "H", data is outputted

from left channel, or when "L", from right channel. Frequency of this clock is

44.1 kHz. Typical duty factor of this signal is 50 %.

WCO...

Frequency of this clock is 88.2 kHz. Typical duty factor of this signal is 50 %.

DO3-0...

These pins output serial audio data as follows.

DO3...

Outputs data of Wavetable whose effect send level has been adjusted.

DO2...

Outputs data that is the mixture of those of FM and Wavetable.

DO1...

Outputs Wavetable data.

DO0...

Outputs FM data.

Format of the serial audio interface is as follows.

15 14 13 12

BCO

DO3-0

24 BCO

LRO

WCO

Format of YMF721 (OPL4-ML2) serial audio interface

Left Channel

Right Channel

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