YMF721 Datasheet, PDF (10/41 Pages) LSI Computer Systems – FM + Wavetable Synthesizer LSI

YMF721
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.
BCO
DO3-0 1 0
LRO
WCO
24 BCO
24 BCO
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Left Channel
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Right Channel
Format of YMF721 (OPL4-ML2) serial audio interface
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July 10, 1997