Rohm LAPIS SEMICONDUCTOR ML620Q503, User Manual

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ML620Q503/Q504 User's Manual
Chapter 23 Melody Driver
FEUL620Q504 23-7
23.3 Description of Operation
23.3.1 Operation of Melody Output
Melody is output in the following procedure.
(1)
Select melody mode by setting the BZMD bit of the melody 0 control register (MD0CON) to “0”.
(2) Set a melody tempo in the melody 0 tempo code register (MD0TMP).
(3) Set a tone length code in the melody 0 tone length code register (MD0LEN).
(4) Set a scale code in the melody 0 scale code register (MD0TON).
(5) When the M0RUN bit of the melody 0 control register (MD0CON) is set to “1”, the tone length code and
scale code are transferred to the tone length buffer and scale buffer and melody output is started from the
MD0 pin. At the same time, a melody 0 interrupt (MD0INT) is requested. When an interrupt occurs and
program is passed to the interrupt routine, the interrupt request flag is cleared.
The melody 0 signal output pin (MD0) is assigned as the secondary function of Port 3 or Port 4 or Port 5. For the
secondary function of Port 3 or Port 4 or Port 5, see Chapter 20, "Port 3" or Chapter 21, "Port 4", Chapter 22,
"Port 5".
In the software processing after melody 0 interrupt, the tone length code and the scale code of the note that are
output next are set to MD0LEN and MD0TON, respectively. When there is no next note to be output, rest data
“00H” is set in MD0TON, the M0RUN bit is set to “0” by the software processing after the next melody 0
interrupt, and melody output is terminated.
By setting the M0RUN bit to “0”, melody can be terminated forcibly during melody output.
Figure 23-2 shows the operation waveform of the melody driver.
Figure 23-2 Operation Waveform of Melody Driver
M0RUN
MD0INT
XX 1
st
sound 2
nd
sound
XX
1
st
sound waveform
2
nd
sound
3
rd
sound
3
rd
sound
Final sound
Rest data
Final sound
Rest data
MD0LEN
MD0TON
Tone length/Scale buffer
Melody output waveform
MD0*
2
nd
sound
waveform
3
rd
sound
waveform
1
st
sound
Final sound waveform