HT36F2 datasheet(15/36 Pages) HOLTEK

15 / 36 page

HT36F2

Rev. 1.00

August 15, 2005

· 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 6.4MHz, the formula of a tone fre-

quency is:

fOUT=fRECORD x

25kHz

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=98Hz.

Can be obtained by using the fomula:

98Hz= 261Hz x

25kHz

11025Hz

FR11 ~ FR0

(17 BL3~BL0)

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

determined when the fOSC is 6.4MHz.

· Start address definition

The HT36F2 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 ST15~ST0 is used to define the start address of

each PCM code and reads the waveform data from

this location. The HT36F2 provides 16 input data lines

from WA15~WA0, the ST15~ST0 is used to locate the

major 12 bits i.e. WA15~WA5 and the undefined data

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

words, the WA15~WA0=ST15~ST0

´25. So each

PCM code has to be located at a multiple of 32. Other-

wise, the PCM code will not be read out correctly be-

cause it has a wrong start code.

· Waveform format definition

The HT36F2 accepts two waveform formats to ensure

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 become close.

The RE12~RE0 is used to calculate the repeat ad-

dress of the PCM code. The process for setting the

RE12~RE0 is to write the 2

¢s complement of the re-

peat length to RE12~RE0, with the highest carry ig-

nored. The HT36F2 will get the repeat address by

adding the RE12~RE0 to the address of the end code,

then jump to the address to repeat this range.

· Volume control

The HT36F2 provides the volume control independ-

ently. The volume are controlled by VR9~VR0 respec-

tively. The chip provides 1024 levels of controllable

volume, the 000H is the maximum and 3FFH is the

minimum output volume.

· The PCM code definition

The HT36F2 can only solve the voice format of the

signed 8-bit or 12-bit raw PCM. And the MCU will take

the voice code 80H as the end code.

So each PCM code section must be ended with the

end code 80H.

· Digital to Analog Converter - DAC

The HT36F2 provides one 16-bit voltage type DAC

device controlled by the MCU or Wavetable Synthe-

sizer for driving the external speaker through an exter-

nal NPN transistor. It is in fact an optional object used

for Wavetable Synthesizer DAC or general DAC, this

is chosen by Mask Option and DAC control register. If

the general DAC is chosen for application, then the

Wavetable Synthesizer is disabled since the DAC is

taken up and controlled by the MCU. If general DAC is

selected, the programmer must write the voice data to

log data. If Mask Option enables the DAC register and

the SELW, then the following table comes useful.

Bit No.

Label

Function

Bit7~Bit3

No used

Bit1

DAON

DAON=1: DAC ON

DAON=0: DAC OFF (Default)

Bit0

SELWR

SELWR=1, Right Channel

DAC data from Wavetable

SELWR=0, Right Channel

DAC data from MCU (Default)

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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