SNC374

Direct Drive Voice/Dual Tone Melody Controller

5 FUNCTION DESCRIPTIONS

5.1. Oscillator

SNC374 accept RC type oscillator for system clock. The typical circuit diagram for

oscillator is listed as follow.

OSC

VCC

RC Oscillator

5.2. ROM

SNC374 contains substantial 132K words (10-bit) internal ROM. Program, voices and

other data are shared with this same 132K words ROM.

5.3. RAM

SNC374 contains 128 nibbles RAM. The 128 nibbles RAM are divided into eight

pages (page 0 to page 7, 16 nibbles RAM on each page).

In our programming

structure, users can easily define and locate RAM page in the program. For instance,

users can use the instructions, PAGEn (n=0 to 7) to switch and indicate the RAM page.

Besides, users can use direct mode, M0 ~ M15 in the data transfer type instructions, to

access all 16 nibbles of each page.

5.4. Power Down Mode

“End” instruction will power down SNC374 and enable IC to consume fewer current for

power saving. (<3uA @VDD=3V and <5uA @VDD=5V) Please be aware that when

the power down mode is activated in SNC374, any valid data transition (L H or H L)

occurring on any input port (P1) or IO ports (P2, P3 and P6) will lead SNC374 back to

normal operation mode.

5.5. Sampling Rate Counter

The unique sampling rate counter is designed in voice channel to be able to play

diverse voices at different sample playing rates. The playing rate can be adaptively

set up among from the wide ranges of 2.5KHz to 20KHz. This feature makes voice

close to its original source and yield the better voice quality.

Ver: 1.2

December 26, 2002

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