YMF721

July 10, 1997

- 13 -

<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.

<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.

<Power Down out>

<Power Down in>

System Exclusive : F0h, 43h, 79h, 04h,0Eh, 6Dh, F7h

receiving MIDI F8h

receiving MIDI E0h

(wait time ~100 msec)

all clock (X’tal)disable

Synthesizer clock disable

Synthesizer clock enable

Normal Operation

Power down sequence without ISA bus

receiving MIDI F8h

~30msec

~3msec