SN52020

2-Channel Speech Controller

5.

FUNCTION DESCRIPTIONS

5.1. Oscillator

SN52020 series accepts crystal oscillator / ceramic resonator or RC type oscillator

(selected by pin CKSEL) for system clock. The typical circuit diagrams for oscillator

are listed as follows.

OSC/XIN

CKSEL

XOUT

VDD

RC Oscillator

Crystal / Resonator

VDD

OSC/XIN

CKSEL

XOUT

15pf

2MHz

SN52000

SN52000

15pf

5.2. ROM

SN52020 contains 64K word (10-bit) internal ROM. Program, voices, melodies, data,

and instrument waveforms share the same ROM with the others.

5.3. RAM

SN52020 series contains 64 nibble RAM. The 64 nibble RAM is separated into four

pages (page 0, page1, page2 and page 3). An implicit page indicator is utilized to

specify page address. Four instructions, PAGE0, PAGE1, PAGE2 and PAGE3, can

switch the page indicator. All 16 nibbles of each page can be accessed by direct mode

(to specify M0 ~ M15 in the data transfer type instructions.)

5.4. Power Down Mode

“End” instruction will let SN52020 enter power down mode and consumer very little

amount of current. (<2uA @VDD=3V and <5uA @VDD=5V) After SN52020 enters

power down mode, any valid data transition (L H or H L) occurring on any P3 IO

ports would lead SN52020 back to normal operation mode.

5.5. Sampling Rate Counters

2 independent sampling rate counters are dedicated to 2 individual voice channels to

play voices with different playing rates. The playing rate is programmable from 4KHz

to 40KHz. The resolution of sampling period of each sampling rate counter is 0.25 uS.

This feature helps SN52020 play sounds with accurate pitches in the case of music

instrument synthesis.

Ver: 1.0

March 2,2005

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