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