HT817D0 Datasheet, PDF (6/15 Pages) Holtek Semiconductor Inc – 16.8-Second LOG-PCM Speech

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 16.8-second voice data at a 6kHz
sampling rate. A higher sampling rate can gener-
ate voices of better playback quality, but will
shorten the total recording time. On the other
hand, a lower sampling rate results in longer re-
cording 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 voice ROM. During programming,
the customer¢s voice sources can be divided 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 sections in-
cluded should be less than 508 due to the space
limitation of the function table ROM. The total
length of the included sections is limited by
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:
E x a m p le 1 : O n e s e c tio n o n ly
s e c .1
ROM
E x a m p le 2 : 3 s e c tio n d iv is io n
s e c .1
s e c .2
s e c .3
ROM
E x a m p le 3 : N s e c tio n d iv is io n
s e c .1 s e c .2
s e c .N
ROM
HT817D0
In addition, a section can be set as retriggerable
or non-retriggerable depending on the code op-
tion.
· _{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.
Of 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 playing, any key in-
terrupt is ignored.
Group
The HT817D0 plays groups on the basis of 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
comprised by one group only.
Key function table
The sections include in the voice ROM are
played according to the instructions of the key
function table. 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.
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March 15, 2000