YMF721 Datasheet, PDF (13/41 Pages) LSI Computer Systems – FM + Wavetable Synthesizer LSI

YMF721
<Power Down Sequence>
(1) Power Down in
When YMF721 (OPL4-ML2) has received the System Exclusive Message shown above, it goes
into the global power down mode after performing the processes as described in "5-1-1. ISA
BUS Connect System".
(2) Power Down out
Since the clock generation has been disabled, YMF721 (OPL4-ML2) is not able to recover from
the global power down mode by using the System Exclusive Message. Thus, the LSI needs to
receive the "3byte MIDI data" as shown below to recover from the global power down mode.
To resume normal operation through the recovery sequence, waiting time of 50 to 100 msec is
required before the oscillation of crystal stabilizes when internal oscillation is used, or 3 msec or
more before the recovery of clock generated in the synthesizer.
<Power Down in>
System Exclusive : F0h, 43h, 79h, 04h,0Eh, 6Dh, F7h
~30msec
Synthesizer clock disable
<Power Down out>
receiving MIDI F8h
(wait time ~100 msec)
receiving MIDI E0h
all clock (X’tal)disable
receiving MIDI F8h
~3msec
Synthesizer clock enable
Normal Operation
Power down sequence without ISA bus
<Micro-processor Reset>
The internal microprocessor is reset by receiving the above System Exchange Message.
5-2. Suspend/Resume mode
The state of internal processor is suspended by writing "E0h" into the command register before turning
off the power. When the power has been turned on, it can be resumed by resetting it, writing "E1h" into
the command register and then writing data that has been read before suspended.
On FM synthesizer block, check setting KON bit to "0" for all channels before reading out all register
and turning off the power. Write register that has been read after turning on and resetting at the
recovery sequence.
For the details of suspend/resume, refer to 6-3.
Note :
The system that includes YMF721 not connected with ISA bus can not support the suspend/resume function.
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July 10, 1997