HT36A1
·
CH2~0 channel number selection
12 bits i.e. WA15~5 and the undefined data from
WA4~0 is always set as 00000b. In other words, the
WA15~0=ST11~0 ´ 25. So each PCM code has to be
located at a multiple of 32. Otherwise, the PCM code
will not be read out correctly because it has a wrong
start code.
The HT36A1 has a built-in 8 output channels and
CH2~0 is used to define which channel is selected.
When this register is written to, the wavetable synthe-
sizer will automatically output the dedicated PCM
code. So this register is also used as a start playing
key and it has to be written to after all the other
wavetable function registers are already defined.
·
Waveform format definition
The HT36A1 accepts two waveform formats to ensure
a more economical data space. WBS is used to define
the sample format of each PCM code.
·
Change parameter selection
These two bits, VM and FR, are used to define which
register will be updated on this selected channel.
There are two modes that can be selected to reduce
the process of setting the register. Please refer to the
statements of the following table:
¨
¨
WBS=0 means the sample format is 8-bit
WBS=1 means the sample format is 12-bit
The 12-bit sample format allocates location to each
sample data. Please refer to the waveform format
statement as shown below.
VM
0
FR
0
Function
Update all the parameter
Only update the frequency number
Only update the volume
8
-
B
i
t
1
B
2
B
3
B
4
B
5
B
6
B
7
B
8
B
0
1
A
1
s
a
m
p
l
i
n
g
d
a
t
a
c
o
d
e
;
B
m
e
a
n
s
o
n
e
d
a
t
a
b
y
t
e
.
1
0
·
Output frequency definition
1
2
-
B
i
t
H
1
M
1
L
2
L
2
H
2
M
3
H
3
M
3
L
The data on BL3~0 and FR11~0 are used to define the
output speed of the PCM file, i.e. it can be used to
generate the tone scale. When the FR11~0 is 800H
and BL3~0 is 6H, each sample data of the PCM code
will be sent out sequentially.
A
s
a
m
p
l
i
n
g
d
a
t
a
c
o
d
e
N
o
t
e
:
"
1
H
"
H
i
g
w
h
N
i
b
b
l
e
"
"
1
1
M
L
"
M
i
d
d
l
e
N
i
b
b
l
e
"
L
o
N
i
b
b
l
e
When the fOSC is 6.4MHz, the formula of a tone fre-
quency is:
Waveform Format
Repeat number definition
25kHz
FR11~ 0
(17- BL3~0)
f
OUT= fRECORD
´
´
·
SR
2
The repeat number is used to define the address
which is the repeat point of the sample. When the re-
peat number is defined, it will be output from the start
code to the end code once and always output the
range between the repeat address to the end code
(80H) until the volume become close.
where fOUT is the output signal frequency, fRECORD and
SR is the frequency and sampling rate on the sample
code, respectively.
So if a voice code of C3 has been recorded which has
the fRECORD of 261Hz and the SR of 11025Hz, the tone
frequency (fOUT) of G3: fOUT=98Hz.
The RE14~0 is used to calculate the repeat address
of the PCM code. The process for setting the RE14~0
is to write the 2¢s complement of the repeat length to
RE14~0, with the highest carry ignored. The HT36A0
will get the repeat address by adding the RE14~0 to
the address of the end code, then jump to the address
to repeat this range.
Can be obtained by using the fomula:
25kHz
FR11~ 0
(17- BL3~0)
2
98Hz= 261Hz ´
´
11025Hz
A pair of the values FR11~0 and BL3~0 can be deter-
mined when the fOSC is 6.4MHz.
·
Start address definition
·
Left and Right volume control
The HT36A1 provides two address types for extended
use, one is the program ROM address which is pro-
gram counter corresponding with PF value, the other
is the start address of the PCM code.
The HT36A1 provides the left and right volume control
independently. The left and right volume are con-
trolled by VL9~0 and VR9~0 respectively. The chip
provides 1024 levels of controllable volume, the 000H
is the maximum and 3FFH is the minimum output vol-
ume.
The ST11~0 is used to define the start address of
each PCM code and reads the waveform data from
this location. The HT36A1 provides 16 input data lines
from WA15~0, the ST11~0 is used to locate the major
Rev. 1.00
16
August 15, 2005
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
