HT36M4 datasheet(16/24 Pages) HOLTEK

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HT36M4

Rev. 1.10

March 14, 2007

· CH3~CH0 channel number selection

The HT36M4 has a built-in 16 output channels and

CH3~CH0 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

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:

Function

Update all the parameter

Only update the frequency number

Only update the volume

· Output frequency definition

The data on BL3~BL0 and FR11~FR0 are used to de-

fine the output speed of the PCM file, i.e. it can be

used to generate the tone scale. When the FR11~FR0

is 800H and BL3~BL0 is 6H, each sample data of the

PCM code will be sent out sequentially.

When the fOSC is 12.8MHz, the formula of a tone fre-

quency is:

fOUT=fRECORDx

50kHz

FR11 ~ FR0

(17 BL3~BL0)

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=196Hz.

Can be obtained by using the formula:

196Hz= 261Hz x

50kHz

11025Hz

FR11 ~ FR0]

(17 BL3~BL0)

A pair of the values FR11~FR0 and BL3~BL0 can be

determined when the fOSC is 12.8MHz.

· Start address definition

The HT36M4 provides two address types for ex-

tended use, one is the program ROM address which is

program counter corresponding with PF value, the

other is the start address of the PCM code.

The ST11~ST0 is used to define the start address of

each PCM code and reads the waveform data from

this location. The HT36M4 provides 17 input data

lines from WA16~WA0, the ST11~ST0 is used to lo-

cate the major 16 bits i.e. WA16~WA5 and the unde-

fined data from WA4~WA0 is always set as 00000b. In

other words, the WA16~WA0=ST11~ST0

´25´8-bit.

So each PCM code has to be located at a multiple of

32. Otherwise, the PCM code will not be read out cor-

rectly because it has a wrong start code.

· Waveform format definition

The HT36M4 accepts two waveform formats to en-

sure a more economical data space. WBS is used to

define the sample format of each PCM code.

¨ 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.

· 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 becomes close.

The RE14~RE0 is used to calculate the repeat ad-

dress of the PCM code. The process for setting the

RE14~RE0 is to write the 2

¢s complement of the re-

peat length to RE14~RE0, with the highest carry ig-

nored. The HT36M4 will get the repeat address by

adding the RE14~RE0 to the address of the end code,

then jump to the address to repeat this range.

· Left and right volume control

The HT36M4 provides the left and right volume con-

trol independently. The left and right volume are con-

trolled by VL9~VL0 and VR9~VR0 respectively. The

chip provides 1024 levels of controllable volume, the

000H is the maximum and 3FFH is the minimum out-

put volume.

· Envelope type definition

The HT36M4 provides a function to easily program

the envelope by setting the data of ENV1~ENV0 and

A_R. It forms a vibrato effect by a change of the

volume to attach and release alternately.

The A_R signal is used to define the volume change in

attach mode or release mode and ENV1~ENV0 is

used to define which volume control bit will be

changeable. On the attach mode, the control bits will

be sequentially signaled down to 0. On the release

mode, the control bits will be sequentially signaled up

to 1. The relationship is shown in the following table.

1 B

2 B

3 B

4 B

5 B

6 B

7 B

8 B

1 H

1 M

1 L

2 L

2 H

2 M

3 H

3 M

A 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 .

8 - B i t

1 2 - B i t

3 L

N o t e : " 1 H " H i g h N i b b l e

" 1 M " M i d d l e N i b b l e

" 1 L " L o w N i b b l e

A s a m p l i n g d a t a c o d e

Waveform Format

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