HT815D0 datasheet(6/15 Pages) HOLTEK

6 / 15 page

HT815D0

March 15, 2000

The oscillator is turned on when triggered by a

key input. After playing, it is immediately turned

off and the chip goes into the standby state.

Voice ROM

The voice ROM is originally designed to continu-

ously record the 11.2-second voice data at a 6kHz

sampling rate. A higher sampling rate will gener-

ate voices of better playback quality, but will

shorten the total recording time. On the other

hand, a lower sampling rate will result in longer

recording time but sacrifice voice quality.

The playback time can be significantly extended

by making use of coding efficiency, silence play-

ing, section repeating, section cascade, etc.

Section

Section is the basic element constituting the

contents of the voice ROM. During program-

ming, the customer¢s voice sources can be di-

vided into as many sections as required. A

section can be composed of a voice or an interval

of silence. However, the silence length is not

counted in voice ROM. The total number of sec-

tions included should be less than 508 due to

the space limitation of the function table ROM.

The total length of the included sections is lim-

ited by the voice ROM.

A section, when triggered by a key input, can be

played once, repeatedly or cascaded with other

sections, depending on the key function table

instructions.

The following are examples of section division:

In addition, a section can be set as retriggerable or

non-retriggerable depending on the code option.

· Retriggerable

When the currently playing section is set as

retriggerable, it will stop immediately upon

receipt of other key inputs.

· Non-retriggerable

When the currently playing section is selected

as non-retriggerable, it will go on playing till

the whole section is completed, whether or not

there is a key input in the process of playing.

For a key group, some sections can be set as

retriggerable and some as non-retriggerable.

When a retriggerable section of a key group is

playing, any key can be triggered to interrupt

its playing. On the other hand, if it is a

non-retriggerable section is playing, any key in-

terrupt is ignored.

Group

The HT815D0 plays groups according to the

key input. A group can be made up of one or

more sections. When a key is triggered, the cor-

responding group is played immediately. For

example, triggering KEY2 plays group 2, and so

on. The same section is allowed to appear in dif-

ferent groups. However, KEY1 can be made up

of multiple groups when it is optioned as a se-

quential or random key. Otherwise, each key is

composed of one group only.

Key function table

The sections in the voice ROM are played ac-

cording to the instructions of key function ta-

ble. The function table contains group

information as well as playing order of sections

in the groups. Notice that the total number of

sections included in the groups should be less

than 508-the space limitation of the function

table ROM.

se c. 2

s e c . N

se c. 1

s e c . 2

se c. 3

se c. 1

RO M

E x am pl e 1 : O n e s ec t i on o n l y

E x am pl e 2: 3 s ec t i on di v i s i on

E x am p l e 3: N s ec t i on di v i s i on

RO M

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