YMU757B Datasheet, PDF (28/43 Pages) YAMAHA CORPORATION – MA-1C

YMU757B
Operation in FIFO empty state
If FIFO has become empty during reproduction, the musical score data written last is processed continuously until the
next data is entered.
If the last written data is a note data, that note is reproduced continuously.
If the last written data is a rest data, the rest state will be maintained.
Reproduction method assuming occurrence of empty state
In the ordinary melody reproduction, it is prohibited to allow the FIFO empty state to occur. However, utilizing the
above feature enables short sounds produced easily. The interrupt function would not be necessary.
To have short sounds produced, follow the steps as described below.
Short sounds are applicable to 1 to 32 word data block.
If the data block exceeds 33 words, use the regular reproduction procedure utilizing the interrupt function.
1) Complete the procedure of Power ON --> Analog Power Down mode -- Initialized --> STOP in advance. (Please
refer to "State transition description" diagram on page 25.)
2) Start reproduction in the FIFO empty state.
3) Write the data block to be reproduced into FIFO.
4) Immediately after writing (after 0 to 20us), the musical score data are processed internally and reproduction is
started.
As reproduction goes on, the data in FIFO are processed and cleared.
5) When FIFO becomes empty, if the last data in the data block is a note data, that note is reproduced continuously
and if it is a rest data, the rest state is retained until the next data block is written into FIFO.
6) When reproducing the next data block, go to step 3).
To stop reproduction, set "0" for ST. Then the data counter of FIFO will be cleared and the state as described in
step 1) will be restored.
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