SNC542
Two Channel Direct Drive Speech Controller
1
INTRODUCTION
SNC542 is a two-channel voice synthesizer IC with PWM direct drive circuit. It
built-in a 4-bit tiny controller with one 4-bit input port and two 4-bit I/O ports. By
programming through the tiny controller in SNC542, user’s varied applications
including voice section combination, key trigger arrangement, output control, and
other logic functions can be easily implemented.
2
FEATURES
Single power supply 2.4V – 5.5V
16 seconds voice capacity are provided(@6KHZ sample rate)
Built in a 4-bit tiny controller
One 4-bit input port and two 4-bit I/O ports are provided
128*4 bits RAM are provided
52K*10 ROM size are provided for voice data and program
Maximum 16k program ROM is provided
Readable ROM code data
IR carrier signal is provided
Built in a high quality speech synthesizer
Adaptive playing speed from 2.5k-20kHz is provided
Two independent voice channels (Channel 1 + Channel 2→Buo1,Buo2)
Built in a PWM Direct Drive circuit and a fixed current D/A output
System clock : 2MHz
Low Power Reset
Ver: 1.5
1
June 8, 2005
SNC542
Two Channel Direct Drive Speech Controller
3
Block Diagram
ROM
Program/Speech
52K×10 bits
Address Pointers/ STACK
SRAM (128 nibbles)
Timer
ALU
IO1
Timing
Generator
OSC
Sampling Rate Counter
×
2
PWM
D/A
IO3
Voice
Synthesizer
IO2
4
PIN ASSIGNMENT
Symbol
P13 ~ P10
P23 ~ P20
P33 ~ P30
VDD
GND
RST
OSC
BUO1/VO
BUO2
I/O
I
I/O
I/O
P
P
I
O
O
O
Function Description
Bit3 ~ Bit0 of Input port 1
Bit3 ~ Bit0 of I/O port 2
Bit3 ~ Bit0 of I/O port 3
Positive power supply
Negative power supply
Reset pin (active high)
Oscillator / Crystal Out
Positive Output of PWM or DA output
Negative Output of PWM
Ver: 1.5
2
June 8, 2005
SNC542
Two Channel Direct Drive Speech Controller
5
FUNCTION DESCRIPTIONS
5.1. Oscillator
SNC542 accept RC type oscillator for system clock. The typical circuit diagram for
oscillator is listed as follow.
VCC
RC Oscillator
5.2. ROM
SNC542 contains substantial 52K words (10-bit) internal ROM. Program, voices and
other data are shared with this same 52K words ROM.
5.3. RAM
SNC542 contains 128 nibbles RAM. The 128 nibbles RAM are divided into eight
pages (page 0 to page 7, 16 nibble 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 SNC542 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 SNC542, any valid data transition (L H or H L)
occurring on any input port (P1) or IO ports (P2 and P3) will lead SNC542 back to
normal operation mode.
5.5. Sampling Rate Counters
2 independent sampling rate counters are dedicated to 2 individual voice channels 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: 1.5
3
r
June 8, 2005
OSC
SNC542
Two Channel Direct Drive Speech Controller
5.6. I/O Ports
P1 is a 4-bit input port and P2/P3 are two 4-bit I/O ports. Any bit of P2 and P3 can
be programmed as either input or output port individually. Any valid data transition
(H L or L H) of P1, P2 and P3 can reactivate the chip when the chip is in
power-down mode.
PAD
To Internal Data Bus
Read Control
Weak
Input Port Configuration (P10~P13)
Port Data
PAD
Port Status
Weak
To Internal Data Bus
Read Control
I/O Port Configuration (P20~P23, P30~P33)
Note: weak N-MOS’s can serve as pull-low resistors.
Ver: 1.5
4
June 8, 2005
SNC542
Two Channel Direct Drive Speech Controller
5.7. IR Function
P33 can be modulated with 38.5KHz square wave before sent out to P33 pin. The IR
signal can be achieved by this modulated signal.
38.5KHZ
"1"
PAD
Mode
P33
5.8. DAC & PWM
SNC542 is an advanced chip to be designed having two optimal methods to play out
the voices. One is DAC and the other is PWM. Upon user’s applications, user can
select either DAC or PWM in his design. Please be aware that only one method can
be activated at a time.
DAC:
A 7-bit current type digital-to-analog converter is built-in SNC542. The
relationship between input digital data and output analog current signal is listed
in the following table. Also, the recommended application circuit is illustrated as
follows.
Input data
0
1
…
N
…
127
Typical value of output current (mA)
0
3/127
n*(3/127)
3
Ver: 1.5
5
June 8, 2005
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