SM5M2

- 16 -

CONTROL PROCEDURE

The binary counter for designating the address of

the melody ROM can be arbitrarily set using the

PRE instruction.

A performance is started and

stopped by the RD0-flag to "1" and "0".

The stop code generates a "rest tell signal", and at

the same time, sets the RD1 flag. The end of the

melody can be found by testing the RD1 flag.

Accordingly, to stop a performance at the end of

melody, the RD0 flag must be clear upon detection

of RD1 flag = 1.

Next step of PRE instruction, put the NOP

instruction.

The following is an example of a melody

generating program.

MELO

LAX

2

ATX

LAX

1

PRE

; Set the starting address of

the melody at the 21st.

Hexadecimal step.

NOP

; Dummy command

:

:

LBLX

0DH

LAX

1

OUT

; Start the melody

TPB

1

; Executed for clear the

RD1 flag

NOP

; Dummy command

:

:

LBLX

0DH

L1

TPB

1

; Test the RD1 flag

TR

L1

; Loop for detect the stop

code

LAX

0

OUT

; Stop the melody

Using these functions, the user can generate

music, sound effects, alarm signals, etc. as desired,

and any portion of the music can be repeated.

Table 3 lists the melody output frequencies. The

output frequency can be halved by making bit 5

Table 3

Melody Output Frequency

∗1 Number of clocks for one cycle

∗2 The number (n) in the waveforms represents the number of periods of the oscillation frequency (32.768 kHz) from the crystal

oscillator for the duration in that particular part of the waveform.

OUTPUT FREQUENCY (Hz) CLOCK NUMBER

∗1

∗2

do

0 0 1 0

2114.1

15.5

si

0 0 1 1

1985.9

16.5

la#

0 1 0 0

1872.4

17.5

la

0 1 0 1

1771.2

18.5

sol#

0 1 1 0

1680.4

19.5

sol

0 1 1 1

1560.4

21.0

fa#

1 0 0 0

1489.5

22.0

fa

1 0 0 1

1394.4

23.5

mi

1 0 1 0

1310.7

25.0

re#

1 0 1 1

1236.5

26.5

re

1 1 0 0

1170.3

28.0

do#

1 1 0 1

1110.8

29.5

7

8

8

8

8

8

8

9

8

9

9

9

9

9

9

10

9

10

10

10

10

11

10

11

11

11

11

11

11

12

12

12

12

13

12

13

13

13

13

14

14

14

14

14

14

15

15

15