NSAM265SR Datasheet, PDF (29/58 Pages) National Semiconductor (TI) – CompactSPEECH Digital Speech Processors

3 0 Command Set (Continued)
SV
Set Vocabulary Type type id
NSAM265SR
NSAM265SF
This command selects the vocabulary table to be used for
voice synthesis The vocabulary type is set according to the
1-byte type parameter
0 Internal vocabulary (default)
1 External vocabulary in ROM
2 External vocabulary in AFLASH (NSAM265SF only)
all others Reserved
If type is 0 id is ignored
Each external vocabulary table has a unique id which is part
of the vocabulary internal header (See the IVS User’s Manu-
al for more details) If type is 1 or 2 the CompactSPEECH
searches for the one byte id parameter in each vocabulary
table header until a match is found
If the id parameter does not point to a valid IVS vocabulary
ERR PARAM is set in the error word
SW
NSAM265SR
Say Words n word₁ word_n
NSAM265SF
This command accepts the number of words to synthesize
(n 1 byte) followed by the indexes of the words (1 byte
each) in the current vocabulary n can be 1 to 8 It plays the
words On completion the EV NORMAL END bit in the
status word is set and the MWRQST signal goes low
If one of the words is not defined in the current vocabulary
or if it is an IVS control or option code ERR PARAM is set
in the error word
TUNE
Tune index parameter value
NSAM265SR
NSAM265SF
Sets the value of the tunable parameter identified by index
(one byte) to the 2-byte value parameter value This com-
mand may be used to tune the DSP algorithms to a specific
Data Access Arrangement (DAA) interface or to change
other parameters If you do not use TUNE the Compact-
SPEECH uses default values
If index does not point to a valid tunable parameter ERR
PARAM is set in the error word
Note The tunable parameters are assigned with their default values on
application of power The INIT command does not affect these pa-
rameters
Table 3-1 describes the tunable parameters their index
numbers and their default values
TABLE 3-1 Tunable Parameters
Index
Parameter Name
Description
Default
0 – 3 Reserved
4
SIL THRESHOLD
Prevents speech from being interpreted as silence The silence detection
algorithm has an adaptive threshold which is changed according to the noise
level This parameter is therefore only the initial threshold level
Legal values 9216 to 13824 in 512 (6 dB) steps
11264
5
SIL THRESHOLD STEP Defines the adaptive threshold changes step If this threshold is too low the
12
threshold converges too slowly If this threshold is too high silence detection is
too sensitive to any noise
Legal values 3 to 48
6
SIL BURST THRESHOLD The minimum time period for speech detection during silence As this threshold
2
increases the time period interpreted as silence increases If this threshold is
too low speech is detected if there is a burst of noise If it is too high words may
be partially cut off
Legal values 1 to 3
7
SIL HANG THRESHOLD The minimum time period for silence detection during speech As this threshold 15
increases the time period interpreted as silence decreases If this threshold is
too low words may be partially cut off If it is too high silence is detected
Legal values 8 to 31
8
SIL ENABLE
Silence compression control
1
0 turns silence compression off
9
ENERGY FACTOR
Determines the energy level used to synthesize silence The default value
means that the energy level of the synthesized silence will be the same as the
energy level of the recorded silence
If you divide (multiply) the default value by two the synthesized silence will be 6
dB less (more) than the level of the recorded silence
Legal values 1024 to 16384
8192
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