SM1126 Ver la hoja de datos (PDF) - Nippon Precision Circuits
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SM1126 Datasheet PDF : 18 Pages
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SM1126 Series
Serial inputs
Serial data is input on SIO in sync with the SC clock in 8-bit units when ST is LOW. Data is not accepted
when ST is HIGH. When ST goes HIGH, the 8-bit data is latched. Note that if the input data exceeds 8 bits in
length, the most recent 8 bits are used and any preceding bits are ignored. Data is in MSB first format.
Input data is interpreted as a command or as a data word (in write mode), depending on the current operating
mode of the device. There are 3 types of commands:
s Playback start command
s SRAM write command
s End-of-write command
The SRAM write command is used to invoke write mode operation, and end-of-write command is used to
return to play mode operation. In write mode, however, data is interpreted as data words to be written to
SRAM.
Note that pin SIO is an output pin only when the parity check command is executed. At all other times, SIO
is an input pin.
Invalid
Data
Valid
Data
SIO
? ? B7 B6 B5 B4 B3 B2 B1 B0
SC
ST
Invalid
Data
??????????
Pin SC should be LOW when either a LOW-to-HIGH or HIGH-to-LOW transition occurs on pin ST.
Figure 4. Serial input timing
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 SIO and SC, as shown in table 2.
The melody select command comprises a fixed code (1000) followed by 4 melody select data bits (B3 to B0).
The 8 bits of data are retained even after playback. If serial data is input during playback, the data is ignored
and playback continues.
SIO
Invalid
Data
Valid
Data
? ? H L L L B3 B2 B1 B0
SC
ST
MTO
Invalid
Data
??????????
Pin SC should be LOW when either a LOW-to-HIGH or HIGH-to-LOW transition occurs on pin ST.
Figure 5. Serial data input timing
NIPPON PRECISION CIRCUITS—7
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