EM73962A
4-BIT MICROCONTROLLER
SOUND EFFECT
EM73962A has a built-in sound generator. It includes the tone generator, random generator and volume control.
The tone generator is a binary down counter and the random generator is a 9-bit linear feedback shift register.
When the CPU is reseted or sleeping, the sound generator is disabled and the output pin (SOUND) is low.
P.30
P23,P24
f1
Tone
fb
3 kinds
of divider
÷2
÷2
generator
f2x2
Output
control
Low
Random
generator
SOUND
PWM
volume control
P17
Sound generator command register
There are 3 kinds of basic frequency for sound generator which can be selected by P30. The output of sound
effect is tone and random combination.
Port30
3
2
1
0
BFREQ SMODE
Initial value : 0000
SMODE
BFREQ Basic frequency (f1) select
Sound generator mode
Disable
0
0
1
1
0
1
0
1
240 KHz
120 KHz
60 KHz
0
0
1
1
0
1
0
1
Tone output
Random output
Tone+random output
don't care
Tone frequency register
The 8-bit tone frequency register is P24 and P23. The tone frequency will be changed when user output the
different data to P23. Thus, the data must be output to P24 before P23 when user want to change the 8-bit
tone frequency (TF).
Port24
Port23
3
2
1
0
3
2
1
0
Initial value : 1111 1111
Higher nibble register
Lower nibble register
** f1=240K/2X, f2=f1/(TF+1)/2, TF=1~255, TF≠0
** Example : BFREQ=10, TF=00110001B.
f1=60K Hz, f2=60K Hz/50/2=600 Hz
Random generator
f(x)=x9+x4+1
+
1
2
3
4
5
6
7
8
9
* This specification are subject to be changed without notice.
10.8.2001
21
ELAN [ ELAN MICROELECTRONICS CORP ]
