When it comes to writing a mopeds or motorcycle in a group there will sometimes be a verbal communication problem
but that doesn't have to be this way because most helmets come with indentations on the inside where you can mount speakers and
Thus use modern communication systems like this Kardos gala, right  but cost high
What is not awesome though is its high price? Which got me thinking?
Whether it is possible to use the Arduino development boards to create a walkie talkie
duplex mode can receive and transmit audio
So in this video, let me show you  how to build DIY method
But let me already warned you then. It does not come with decent audio quality
Nevertheless though. Let's get started
This video is sponsored by jl CPC beer where you can get $2 PCBs super easily
also a customer feedback is getting discussed and
Evaluated within the company to constantly improve the PCB ordering process
Which you can experience yourself by uploading yokubou files today
To start off I had to think about how a walkie talkie  buid know basic principle
It's most important peripheral features for this job or its 16-bit timer, and it's ten bits ADC
But of course we firstly need an audio signal that we want to transmit
For that I got myself those flexible microphones, which come over 3.5 millimeter stereo
jack and are built around a simple contents a microphone that
Means all I had to do was to add a 10 kilo
Ohm, resistor 10 mukha farad capacitor and the voltage source to the stereo
You check like it is shown here in order to get an AC voltage audio signal right after the capacitor
This audio signal needs to get samples by the ADC or analog to digital converter of the microcontroller
In order to turn the analog voltages of the signal into digital values that we can let ascend
This also requires the 16-bit timer though in order to trigger one a DC conversion
For example, every sixty two point five microseconds, which would equal a sampling rate of 16. Kilo Hertz
This sampling rage does of course not offer the best audio quality
But let's play it safe for this first experiments and let's rather focus on a bigger problem
These small peak to peak voltages of only around 100 millivolts of our audio signal
Due to them these samples digital values would only differ slightly
Which could lead to distortion problems later on?
let we use lm358 operational amplifier which works with a minimum voltage of 3 volts
which will be important later on and
Created a simple inverting amplifier bovitz on a breadboards with a gain of 100
connect microphone see the result
So now that our microcontroller cut our audio signal digitalized
We need a way to wirelessly send it over to another microcontroller
For that I wanted to use the NIF 24 l 0 1 + 2.4 gigahertz transceiver
Because I not only used them successfully before
But also because I had those long-range antenna ones laying around for quite a while
so after 1 NIF 24 transmitted the audio data, and another one received at the
second receiving microcontroller will once again use its tama one with its output pins 9 and 10 to create a
PWM signal
changing duty cycle according to the received audio signal
This way the quickly changing
PWM signal does not only look fascinating
lets hear sound by connecting speaker
That is how a basic Audrina walkie-talkie could function
All that was left to do was to write the fitting code for its
Luckily though before I started losing my mind creating such a complicated codes. I found the RF 24 audio library
Which apparently offers real-time audio streaming and comes with pretty awesome features?
After downloading its and having a look at its codes
I realized that it's more or less follows the functional steps of not win a walkie talkie here. I mentioned early on
So I opened its minimal sketch in order to determine the most important pins for the components
except for the volume control pins, which I pretty much scrapped by simply setting the volume to the maximum and
Then created a suitable schematic for my first bread for tests
It is important to note though that the NIF 24 requires a powerful 3.3 volt power source
Which is why for my later PCB prototype?
I made my life easier by simply powering all the components with 3.3 volts
But nevertheless after I pulled up one transmitter and one receiver on a breadboard
Uploading these slightly modified codes and powering everything
It seemed like the transmitted audio data was properly received
Indicated by the receive status LED connected to pin 6
But on the other hands the audio quality was quite terrible
Listen for yourself
At this point I thought the breadboard construction was the culprits for this bad quality and
Thus decided to move on with a PCB prototype
For that a fousey decided on the size of the PCB and where to position the jack plugs for the microphone and the headphones
Since the speaker was too quiet for my tastes the locking push button to start the transmission
The micro USB inputs for power a power switch and finally a small 100. Kilo. Ohm potentiometer
To set the gain of the microphone amplifier. I
Did this because at this point I was still convinced that I would mount the system
Along with a small power bank to my helmets and actually uses
So as soon as the blueprint of my PCB design was completes
I created a proper fully fledged schematic for my walkie. Talkie
Which through the help of eazy-e da I then converted into a PCB design
It took me roughly around four hours to position all the components as close to one another as possible
While still being able to do all the routing successfully on the top and bottom sites
and as soon as I was happy with my design
I ordered five PCBs of its through which il CPC beer for only two dollars after
Waiting for week. I received the PCBs which like always made a positive first impression and
once I sourced all of the required components
I firstly sold out all SMD components to two PCBs and
Then moved on by soldering in only tht components which all an old took me around three hours
Now to program the microcontrollers, I used an Arduino Uno as a programmer
Which I hooked up to the PCBs according to this wiring scheme
In the arduino ide I then simply had to choose the correct
microcontroller ports and the arduino si SP and click upload using programmer as
You can see the uploading worked out smoothly and thus I repeated this process
For the other pc beer and then hooked up all the external components and finally power
Just like before both PCBs can talk with one another
But the audio quality was so bad that it is pretty much unusable
Now I tried a couple of things like altering the sampling rate and transfer speeds and
Also improving the microphone amplifier circuits, but nothing helped to improve the audio quality
So me telling you that the transmitting range of around 50 meters is okay
the current consumption of 50 milliamps would guarantee a long run time and
That designing a suitable housing for mounting. The PCBs worked out smoothly is not necessary anymore
Because for me this Arduino walkie-talkie was a big failure. I
Guess sticking to dedicated wireless audio streaming
Isis would have been the way to go which I might try out in a future video but
nevertheless feel free to pick up my design schematic and PCB of the projects in
Order to maybe even fix an obvious and dumb mistake. I made I
Hope you enjoyed this video anyway, and learned bits about wireless
Audio transmission even though my practical application did not work out as plans
