SM1125_06 Datasheet, PDF (6/13 Pages) Nippon Precision Circuits Inc – Multimelody IC for Pagers

SM1125 series
Playback control
The ST pin controls the start of playback. While ST is HIGH, the melody is played repeatedly, and when ST
goes LOW, playback stops. Melodies are selected by input serial data on pins SI and SC, as shown in table 2.
The final 4 serial data bits in any input data string form the valid selection data, and this data is retained even
after playback. If serial data is input during playback, the data is ignored and playback continues.
Invalid Valid
Data Data
SI ? ? B3 B2 B1 B0
Invalid
Data
????
SC
ST
MTO
Pin SC should be LOW when either a LOW-to-HIGH or HIGH-to-LOW transition occurs on pin ST.
Figure 4. Serial data input timing
Serial data selection
Table 2. Serial data melody select
B3 B2 B1 B0
ST
L
L
L
L
L→H
L
L
L
H
L→H
L
L
H
L
L→H
L
L
H
H
L→H
L
H
L
L
L→H
L
H
L
H
L→H
L
H
H
L
L→H
L
H
H
H
L→H
Melody
1st melody
2nd melody
3rd melody
4th melody
5th melody
6th melody
7th melody
8th melody
B3 B2 B1 B0
ST
H
L
L
L
L→H
H
L
L
H
L→H
H
L
H
L
L→H
H
L
H
H
L→H
H
H
L
L
L→H
H
H
L
H
L→H
H
H
H
L
L→H
H
H
H
H
L→H
Melody
9th melody
10th melody
11th melody
12th melody
13th melody
14th melody
15th melody
16th melody
SI
SC
ST
MTO
#n1 Data
#n2 Data
#n1 Play #n1 Play #n1 Play
#n2 Play
Melody plays repeatedly when ST is HIGH, and stops immediately when ST goes LOW.
Figure 5. Melody repetition timing
SEIKO NPC CORPORATION —6