SM1155 series

NIPPON PRECISION CIRCUITS—5

Power-save Function

As shown in the preceding timing diagrams, the oscillator stops during non-play mode and the pull-down resis-

tance value changes in response to both HIGH-level and LOW-level inputs (power-save pull-down resistor) to

reduce power consumption and extend battery life.

Non-play oscillator stop function

When melody play ends, regardless of the state of TG, the internal oscillator stops and is placed in a standby

exceed 3.3µA.

Power-save pull-down resistor

The resistance of the TG input pull-down resistor changes in response to the input voltage. The pull-down

resistance is 500k

Ω when the input is HIGH, and the pull-down resistance is 135kΩ when the input is LOW.

Furthermore, if a light-dependent resistor (CdS) cell is employed as a switch (the pull-down resistance is max-

imum when the CdS resistance is minimum (light) and the pull-down resistance is minimum when the CdS

resistance is maximum (dark)), the combined resistance can be increased, decreasing current consumption.

Musical Specifications

Maximum program steps

A maximum of 64 steps can be programmed into internal mask-programmable ROM. Each step represents

either a note (sound pitch and length), a rest note, or a jump. The maximum number of jumps is 7.

Note length (including rests)

Eight rhythm values, from sixteenth note to half note, for notes and rests can be programmed, as shown in the

following table.

Also, notes and rests longer than half notes and rests can be created using a tie to connect the notes. This

requires 2 program steps in ROM.

Tempo

The tempo for the standard quarter note can be selected from the following 16 options.

Pitch and scale

form a scale.

Type

Code

01234567

Note

Rest

Code

0123456789

A

B

C

D

E

F

=

6 9 7

3 4 8

2 3 2

1 7 4

1 3 9

1 1 6

99.4

8 7

77.3

69.6

63.3

5 8

53.5

49.7

46.4

43.5