Silicon Chip – July 2019

44 Silicon chip Australia’s electronics magazine siliconchip.com.au

Speech Synthesiser

Raspberry Pi Zero

Speech Synthesiser

with

the

Raspberry Pi Zero

Most electronic devices communicate with us via blinking lights.

But humans use speech to communicate virtually any concept easily and

clearly. So wouldn’t it be better if your electronic gadgets spoke to you? Now

you can make them do just that, with a low-cost Raspberry Pi and our simple

hardware and software, in just about any language. They can even play music!

by Tim Blythman

The completed Speech Synthesiser consists of a small

PCB fitted to a Raspberry Pi Zero board, and measures

only 65mm by 31mm and is capable of directly driving a

small pair of stereo speakers. We show it here connected

to a Arduino board, although any microcontroller or

computer which provides a serial interface can be used

to control the Speech Synthesiser.

W

e have published sever-

al projects over the years

which can be used to play

back sounds, and many of these can

be (and have been) used to play back

recorded voice samples to indicate to

a user what is going on inside an elec-

tronic device.

But you’re usually limited to just a

handful of voice samples, restricting

the information that you can convey

with such devices.

Not so with this one, which can gen-

erate a virtually unlimited number of

different phrases, short or long. They

broadcast clearly, in the language of

your choice, and with the option

of several different accents.

You just need to feed

in text over a serial port

(eg, from just about

any microcontroller

or computer), and

it will be translated into sound.

These days, pretty much every

portable electronic device (and some

which are intended to be placed

around the home) can speak to its

users.

We wanted to be able to add that

capability to any microcontroller-

based project in a compact and low-

cost package, and that is what we have

achieved.

Various speech options

Single-chip ‘speech solutions’ do

exist, such as the SpeakJet (www.mag-

nevation.com/SpeakJet.swf).

While capable of generating speech

and other sound effects, it still requires

an external filter and amplifier.

The SpeakJet IC costs over $50, and

while impressive in what it does for

its size, we think our solution is com-

petitive on cost and versatility, even

if it is slightly larger.

We’ve also seen an Arduino speech

shield, closer to $100 in cost, which

is more expensive than our solution

and also larger.