SPC41B1 Sunplus Technology Co., Ltd., SPC41B1 Datasheet - Page 7

• Manufacturer Part Number: SPC41B1
• Description: 40KB SOUND CONTROLLER
• Manufacturer: Sunplus Technology Co., Ltd.

6.8. Timer/Counter
The SPC41B1 contains two 12-bit timer/counters, TMA and TMB
respectively. TMA can be specified as a timer or a counter, but
TMB can only be used as a timer. In the timer mode, TMA and
TMB are re-loaded up-counters.
$0FFF to $0000, the carry signal will make the timer automatically
reload to the user’s pre-set value and be up-counted again. At the
same time, the carry signal will generate the INT signal if the
corresponding bit is enabled in the INT ENABLE Register. If TMA
is specified as a counter, users can reset by loading #0 into the
counter. After the counter has been activated, the value of the
counter can also be read from the counters at the same time.
The read instruction will not affect the value of the counter or reset
it.
Clock source of Timer/Counter can be selected as follows:
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MODE SELECT REGISTER
TIMER CLOCK SELECTOR
TMA
TMB
Timer/Counter
12-BIT COUNTER
12-BIT TIMER
12-BIT TIMER
CPU CLOCK (T) or T/4
T/64, T/8192, T/65536 or EXT
CLK
T or T/4
TMA only, select timer or counter
Select T or T/4
When timer overflows from
Clock Source
7
6.9. Speech and Melody
Since the SPC41B1 provides a large ROM and wide range of CPU
operation speeds, it is most suitable for speech and melody
synthesis.
For speech synthesis, the SPC41B1 can provide NMI for accurate
sampling frequency. Users can record or synthesize the sound
and digitize it into the ROM. The sound data can be played back
in the sequence of the control functions as designed by the user's
program. Several algorithms are recommended for high fidelity
and compression of sound including PCM, LOG PCM, and
ADPCM.
For melody synthesis, the SPC41B1 provides the dual tone mode.
After selecting the dual tone mode, users only need to fill either
TMA or TMB, or both TMA and TMB to generate expected
frequency for each channel. The hardware will toggle the tone
wave automatically without entering into an interrupt service
routine. Users are able to simulate musical instruments or sound
effects by simply controlling the envelope of tone output.
SPC41B1
SEP. 04, 2001
Version: 1.3