Practical Arduino Cool Projects for Open Source Hardware- P18 doc

CHAPTER 9  SPEECH SYNTHESIZER

Figure 9-7. Shielded cable connected to female RCA line plug
tted to an Arduino and plugged into an amplifier you can go to the following
ding a small amplifier to the shield so you can drive a speaker directly is quite easy with the LM386
io amplifier IC. LM386 chips are very common in small audio devices, such as compact portable
radios, because they're very easy to use and produce reasonable quality sound at a good volume level.
They certainly won't compete with the amp in your stereo system, but for simple voice-level output in a
portable device they're perfect.


Once your shield is fi
section “Speech Synthesizer Software” to test it out.
On-Board Amplifier
Ad
aud

Figure 9-8. Pinout of LM386 audio amplifier
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CHAPTER 9  SPEECH SYNTHESIZER
To build a simple audio amplifier with a gain of about 20 you can use the LM386 on
pretty much nothing else required. However, with a few extra parts it can be configured
of about 50. If necessary it can be configured for a gain of up to 200, but that's pushing
it can do and since we're powering the amplifier circuit from the Arduino's 5V supply th
and noise on the supply rails could become a problem. Audio amplifiers pull a lot more
typical digital circuits you might be used to dealing with on an Arduino: since amps equ
by volts, even a tiny 1/4W amplifier running on
its own with
to deliver a gain
the limits of what
e current drain

power than the
als watts divided
a 5V supply can suck down 50mA of current, assuming it
uations
nt but rather jumps
ble balance between a high output volume and low power consumption,
eed to use a
nd also make sure
d version of the output from the SpeakJet, so it uses the
w-pass filter as the line-level output and then adds the LM386 to provide an amplified version of
the signal. Add the LM386 to the shield along with its associated parts, the 10K trimpot and the various
resistors and capacitors, as shown in Figure 9-9. Finally, solder on the PCB-mount two-pin screw
terminal to provide a handy connection for a speaker.

runs at an unrealistic 100% efficiency. Even worse than the current drain, though, are the fluct
that can be induced on the supply rails, since the current consumption isn't consiste
around all over the place depending on the input signal.
A gain of 50 gives a reasona
and won't strain the Arduino's power supply. If you want more volume you'll probably n
more substantial external amplifier and feed it with the line-level output connection, a
the supply rails are adequately filtered.
The LM386 needs to be fed with a filtere
same lo

Figure 9-9. Shield with LM386-based audio amplifier in place and speaker connected
If you have an old speaker from a stereo system you can connect a pair of wires to it and attach them
to the screw terminals. Otherwise, use a small speaker from an electronics parts shop, an old computer
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CHAPTER 9  SPEECH SYNTHESIZER
speaker, or even a speaker out of a car stereo system, and solder two wires to the speake

other ends into the screw terminals on the shie
r. Then insert the
ld.
Turn the trimpot to about halfway as a starting point so it has a reasonable volume level. Mount the
shield on your Arduino, and install the software to test it.
ftware
phones to the
ons at 9600bps we
reSerial library, then specify which pins will be used for RX and TX. We
t the SoftwareSerial RX (receive) pin, because all we'll be doing is sending values
to the SpeakJet and not reading anything back. However, SoftwareSerial needs both to be defined so
we'll set it anyway and then ignore it.
ftwareSerial.h>



s are stored as a series of allophones in an array, so to make it easier to read the array we'll
for the "Word Pause" value that is appended after each word. The SpeakJet
s allophone 6
ly put WP into the
alue.
#define WP 6
e” to hold the allophones for the words we want to speak.
d embedding comments within each line we can make the array much
lue onto the end of each word inserts allophone 6, the word pause.
es it relatively simple to copy and paste different
rds into place to make up your own sentences, as follows:
/* name */ 141, 154, 140, WP,
/* is */ 8, 129, 167, WP,
/* arduino */ 152, 148, 175, 147, 128, 141, 164, WP

};

Later the program will need to know the length of the message array, so rather than count the values
manually and have to update it every time the message is changed we'll instead have the program count
the array elements and store it for future reference.
Speech Synthesizer So
To test the speech synthesizer, start with a minimal program that sends a series of allo
SpeakJet to sound out a simple sentence.
Because the Arduino communicates with the SpeakJet using serial communicati
first need to include the Softwa
don't actually care abou

#include <So

#define rxPin 2
#define txPin 3

Then create a new software serial port object called "speakJet."

SoftwareSerial speakJet = SoftwareSerial(rxPin, txPin);
Word
define a memorable token
has six different pauses available, but the most commonly used pause between words i
which has a duration of 90 milliseconds. By defining WP as the value 6 we can simp
w agic vord array as if it's a single byte, and not have to remember that allophone 6 is a m


Next, we'll set up an array called “messag
By breaking it up visually an
easier to read. Finally, tacking a WP va

Working with the message array this way mak
wo

byte message[] = {
/* hello */ 183, 007, 159, 146, 164, WP, WP,
/* my */ 140, 155, WP,
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CHAPTER 9  SPEECH SYNTHESIZER
int messageSize = sizeof(message);

The setup function is called once when the program starts, and configures the software serial
to the SpeakJet. Since the SpeakJet runs by default at 9600bps we set up the software serial
port to match.

s a special case by
he volume) and 21 (which sets the speaking rate). When the
SpeakJet sees either of these bytes it interprets the next byte as the value for that parameter and updates
se settings are stored in nonvolatile memory inside the SpeakJet.
e to a value of 96 (on a scale of 0 through 127), we first send byte 20 (volume
mmand) followed by a value of 96, as follows:
speakJet.print(20, BYTE);
TE);
Setting the speech rate is done in a similar way. First we send byte 21 (speed command), followed by
speakJet.print(114, BYTE);
the setup function,
olumes and speech rates. The setup function then pauses
for one second to give the SpeakJet time to receive and process the values.
1000);
he main program loop is incredibly simple. It steps through the message
rray using a counter, i, and sends each value it finds to the SpeakJet via the serial connection defined

nds before repeating.
void loop()

speakJet.print(message[i], BYTE);
}
delay (5000);
}

With a short sentence repeated at five second intervals there is plenty of time for the SpeakJet to say
the whole the sentence before it is sent through again, so we are not checking for the Buffer Half Full
state.
connection
void setup()
{
pinMode(rxPin, INPUT);
pinMode(txPin, OUTPUT);
speakJet.begin(9600);

It then sends some initialization values to the SpeakJet. Some bytes are treated a
the SpeakJet, including 20 (which sets t
its internal settings. The
So, to set the volum
co

speakJet.print(96, BY

a value of 114 to set the speaking rate to 114 (on a scale of 0 to 127), as follows:

print( 21, BYTE); speakJet.

Both those settings are actually the default values, but by putting these lines into
it makes it easy to experiment with different v
delay(
}
After all that preparation t
a
earlier. It then pauses for five seco

{
int i;
for (i=0; i<messageSize; i++)
{
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CHAPTER 9  SPEECH SYNTHESIZER
When you power up your Arduino and speech synthesizer shield it will immediately say "ready,"
even if you haven't sent any values to the SpeakJet yet. That's just the SpeakJet's internal self-test
indicating that it has finished and is ready to receive commands.
nds listed below allow you to create any word you want your Arduino to say
hose sounds.
mands and
nt to the SpeakJet. Because the SpeakJet chip can also
function as a multichannel sound synthesizer it has a number of commands other than the ones listed in
hat are relevant to speech synthesis are shown here. Full details of all available
omm ncluded in the SpeakJet datasheet.
Table ommands
Byte Command
Create Your Own Messages
The allophones and comma
by breaking it up into sounds and then creating a list of the bytes that represent t
The SpeakJet accepts one-byte values from 0 to 255, with some values treated as com

others as allophones to sound out.
Low values are used for commands se
Table 9-2. Just the ones t
c ands are i
9-2. SpeakJet c
Pause 3 (7
Pause 4 (30ms
Pause 5 (60ms)
Pause 6 (90ms)
0 Pause 0 (0ms)
1 Pause 1 (100ms)
2 Pause 2 (200ms)
3 00ms)
4 )
5
6
7 Play next sound fast
8 Play next sound slow
14 Stress next phoneme
15 Relax next phoneme
20 Volume X (range 0–127, default 96)
21 Speed X (range 0–127, default 114)
22 Pitch X (range 0–255, default 88)
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CHAPTER 9  SPEECH SYNTHESIZER
23 Bend X (range 0–15, default 5)
30 Delay X (range 0–255 times 10ms increments)

Five of the commands listed in Table 9-2 are two-byte commands. The first byte sent i
command itself, and the second X byte is the value for that parameter. Sending a pair

and then 56, would set the volume to a value of 56.
Value
s the
of bytes, such as 20
s 128 and above are the allophones themselves. Spoken sounds that are used to form words
are values 128 through 199, and are listed in Table 9-3 with the letter representation of the associated
to show the pronunciation, the duration of the sound in milliseconds, and the
type of sound.
Spea
yte Phonem le Words
phoneme, sample words
Table 9-3. kJet allophones
B e Samp Duration Type
128 IY Feed Long Vowel See, Even, 70 Voiced
133 Cotten 70 Voiced
134 U Luck, Up, U 70 Voiced
135 Hot, Clock, F 70 Voiced
129 IH Sit, Fix, Pin 70 Voiced Short Vowel
130 EY Hair, Gate, Beige 70 Voiced Long Vowel
131 EH Met, Check, Red 70 Voiced Short Vowel
132 AY Hat, Fast, Fan 70 Voiced Short Vowel
AX Short Vowel
X ncle Short Vowel
OH ox Short Vowel
136 AW Father, Fall 70 Voiced Short Vowel
137 OW Comb, Over, Hold 70 Voiced Long Vowel
138 UH Book, Could, Should 70 Voiced Short Vowel
139 UW Food, June 70 Voiced Long Vowel
140 MM Milk, Famous 70 Voiced Nasal
141 NE Nip, Danger, Thin 70 Voiced Nasal

142 NO No, Snow, On 70 Voiced Nasal
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CHAPTER 9  SPEECH SYNTHESIZER
143 NGE , Ping iced Nasal
NGO ed Nasal
LE , Lapel ed Resonate
146 LO Clock, Plus, Hello 70 Voiced Resonate
147 WW Wool, Sweat 70 Voiced Resonate
148 RR Ray, Brain, Over 70 Voiced Resonate
RR ear, Year Color Vowel
RR r, Repair Color Vowel
51 RR Color Vowel
152 AWRR Part, Farm, Yarn 200 Voiced R Color Vowel
153 OWRR Corn, Four, Your 185 Voiced R Color Vowel
154 EYIY Gate, Ate, Ray 165 Voiced Diphthong
155 OHIY Mice, Fight, White 200 Voiced Diphthong
56 IY ice Diphthong
57 IH Five, I Diphthong
58 H Diphthong
159 EHLL Saddle, Angle, Spell 140 Voiced Diphthong
160 IYUW Cute, Few 180 Voiced Diphthong
161 AXUW Brown, Clown, Thousand 170 Voiced Diphthong
162 IHWW Two, New, Zoo 170 Voiced Diphthong
163 AYWW Our, Ouch, Owl 200 Voiced Diphthong
164 OWWW Go, Hello, Snow 131 Voiced Diphthong
165 JH Dodge, Jet, Savage 70 Voiced Affricate
Think 70 Vo
144 Hung, Song 70 Voic
145 Lake, Alarm 70 Voic
149 IY Clear, H 200 Voiced R

150 EY Hair, Stai 200 Voiced R
1 AX Fir, Bird, Burn 190 Voiced R
1 OW Boy, Toy, Vo 225 Voiced
1 OH Sky, 185 Voiced
1 IYE Yes, Yarn, Million 170 Voiced
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CHAPTER 9  SPEECH SYNTHESIZER
166 VV t, Even iced Fictive
67 ZZ iced Fictive
68 ZH asure iced Fictive
169 DH There, That, This 70 Voiced Fictive
170 BE Bear, Bird, Beed 45 Voiced Stop
171 BO Bone, Book, Brown 45 Voiced Stop
72 EB eb Voiced Stop
73 OB b, Tub Voiced Stop
74 DE , Date, Divide Voiced Stop
175 DO Do, Dust, Dog 45 Voiced Stop
176 ED Could, Bird 10 Voiced Stop
177 OD Bud, Food 10 Voiced Stop
178 GE Get, Gate, Guest 55 Voiced Stop
79 GO Stop
80 EG d Stop
81 OG g d Stop
182 CH Church, Feature, March 70 Voiceless Affricate
183 HE Help, Hand, Hair 70 Voiceless Fricative
184 HO Hoe, Hot, Hug 70 Voiceless Fricative
185 WH Who, Whale, White 70 Voiceless Fricative
186 FF Food, Effort, Off 70 Voiceless Fricative
187 SE See, Vest, Plus 40 Voiceless Fricative
188 SO So, Sweat 40 Voiceless Fricative

Ves 70 Vo
1 Zoo, Zap 70 Vo
1 Azure, Tre 70 Vo
1 Cab, Crib, W 10
1 Bob, Su 10
1 Deep 45
1 Got, Glue, Goo 55 Voiced
1 Peg, Wig 55 Voice
1 Dog, Pe 55 Voice
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CHAPTER 9  SPEECH SYNTHESIZER
189 SH iction, Leas less Fricative
90 TH onth iceless Fricative
91 TT ittle, Sit iceless Stop
192 TU To, Talk, Ten 70 Voiceless Stop
193 TS Parts, Costs, Robots 170 Voiceless Stop
194 KE Can't, Clown, Key 55 Voiceless Stop
95 KO , Fox iceless Stop
96 EK iceless Stop
197 OK Book, Took, October 45 Voiceless Stop
198 PE People, Computer 99 Voiceless Stop
Ship, F h 50 Voice
1 Thin, M 40 Vo
1 Part, L 50 Vo
1 Comb, Quick 55 Vo
1 Speak, Task 55 Vo

Values 200 a spec ose s s such as sound effects and DTMF tones. These are
listed in Table 9-4.
ab 4. SpeakJet sound effects and tones

yte Phoneme Sample Wor Duration Type
nd above are ial purp ound
T le 9-
B ds
200 R0 80 Robot
201 R1 80 Robot
202 R2 80 Robot
203 R3 80 Robot
204 R4 80 Robot
205 R5 80 Robot
206 R6 80 Robot
207 R7 80 Robot
208 R8 80 Robot

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CHAPTER 9  SPEECH SYNTHESIZER
209 R9 80 Ro
10 A0 300 Alarm
11 A1 101 Alarm
212 A2 102 Alarm
213 A3 540 Alarm
214 A4 530 Alarm
15 A5 500 Alarm
16 A6 135 Alarm
17 A7 600 Alarm
218 A8 300 Alarm
219 A9 250 Alarm
220 B0 200 Beeps
221 B1 270 Beeps
22 B2 280 Beeps

23 B3 260 Beeps
24 B4 300 Beeps
225 B5 100 Beeps
226 B6 104 Beeps
227 B7 100 Beeps
228 B8 270 Beeps
229 B9 262 Beeps
230 C0 160 Biological
231 C1 300 Biological
bot
2
2
2
2
2
2
2
2
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