HT36A1 Holtek Semiconductor Inc., HT36A1 Datasheet - Page 16

• Manufacturer Part Number: HT36A1
• Description: Ht36a1 -- Music Synthesizer 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

Rev. 1.10
CH2~0 channel number selection
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.
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:
Output frequency definition
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.
When the f
quency is:
f
where f
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 f
frequency (f
Can be obtained by using the fomula:
98Hz= 261Hz
A pair of the values FR11~0 and BL3~0 can be deter-
mined when the f
Start address definition
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 ST11~0 is used to define the start address of
each PCM code and reads the waveform data from
this location. The HT36A1 provides 17 input data lines
from WA16~0, the ST11~0 is used to locate the major
OUT
VM
0
0
1
= f
RECORD
RECORD
OUT
FR
0
1
0
is the output signal frequency, f
of 261Hz and the SR of 11025Hz, the tone
OSC
OUT
) of G3: f
is 6.4MHz, the formula of a tone fre-
Update all the parameter
Only update the frequency number
Only update the volume
25kHz
11025Hz
OSC
SR
25kHz
is 6.4MHz.
OUT
2
FR11 ~ 0
=98Hz.
Function
(17 BL3~0)
2
FR11 ~ 0
-
(17 BL3~0)
-
RECORD
and
16
12 bits i.e. WA16~5 and the undefined data from
WA4~0 is always set as 00000b. In other words, the
WA16~0=ST11~0
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.
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.
The 12-bit sample format allocates location to each
sample data. Please refer to the waveform format
statement as shown below.
Repeat number definition
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.
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.
Left and Right volume control
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.
WBS=0 means the sample format is 8-bit
WBS=1 means the sample format is 12-bit
Waveform Format
2
5
8-bit. So each PCM code has
March 12, 2007
HT36A1