SM1126 View Datasheet(PDF) - Nippon Precision Circuits

Part Name

Description

Manufacturer

SM1126

Melody IC with Built-in SRAM

Nippon Precision Circuits  

SM1126 Series

Write Mode Control

Write sequence

The SM1126 Series devices can accept data words written to the built-in SRAM to play any melody. The

SRAM write sequence is described below.

1. Write the SRAM write command (11011111) to invoke write mode.

2. Write the tempo word (parity check ON/OFF selectable).

3. Write all necessary melody data words (parity check ON/OFF selectable).

4. Write the melody end word (parity check ON/OFF selectable).

5. Optionally, write extra data words (these are ignored).

6. Write the end-of-write command (10111111) to return to play mode.

7. If parity check was ON, write the parity check command (01111111) to perform an error check.

The built-in SRAM can store 64 words, so all melody and end words must fit within this limit. Note that the

tempo word is not stored in SRAM, but in a separate register. Playback of melodies stored in SRAM begins

from the SRAM leading address and continues until the end word is detected, at which point playback contin-

ues again from the SRAM leading address. All data in SRAM after the end word is ignored.

Input write command (11011111)

Play mode

Input write command (11011111)

Write tempo word

Write tempo word

Write melody word (s)

Write melody word (s)

Write end word

Write optional invalid data

Write mode

Write end word

Write optional invalid data

Input end-of-write command (10111111)

Input end-of-write command (10111111)

Input parity check command (01111111)

Play mode

Example 1. Parity check selected

Example 2. Parity check not selected

Figure 9. Write control sequence

NIPPON PRECISION CIRCUITS—10

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