Walkie-Talkie using UDP Broadcast and ESP-NOW

Hey Everyone! We've made a Walkie Talkie based around the ESP32! There's a link in the description  to the Fusion360 project   and the STL files for the case - so feel free  to print your own version if you want to. Let's have at what's inside and see how it works. We have the microphone - I've  made space for my own ICS-43434 breakout board and space for the popular INMP441 microphone board. These are both I2S microphones that  interface directly with the ESP32. Above the microphone, we have  an I2S 3W amplifier board   that's powering our speaker. This also  directly interfaces with the ESP32. We have our ESP32 board - I'm using a  TinyPICO here, but you should be able to use any generic ESP32 dev board we're not using any special features in this project. We've got a push-button switch  for controlling transmission. We've got a simple slider switch  to turn the battery on and off. You may have noticed that I'm using a custom  PCB - I got this made up by the great people   at PCBWay - as usual, they did a great job and I'm  really pleased with how the boards have come out. I've got a lot of audio projects and it's really  nice to be able to just plug things together   and not to have to worry about wires going  everywhere. The only slight omission I've made is not breaking out the remaining GPIO pins -  so I think I'll do that in version 2 of the board. I've included a link to both the schematic  and the project on PCBWay in case you want to   order your own version. You can also clone the  project on EasyEDA and customise it as needed. Having said that, you really don't need a  PCB, you can easily just connect everything   up on breadboard - and that's exactly  what I did when I was prototyping. The schematic is very simple - we're using  I2S boards for both the microphone and   the speaker which makes the wiring up of  these to the ESP32 very straightforward. You can of course modify the code to use the  built-in ADC for input and the built-in DAC   for output. Very handy if you want to use analogue  microphone boards and a headphone jack for output. I've added a bit of extra circuitry to my board to  create a clean power supply for the microphones.   If you watch some of my earlier  videos then you'll recall that we   were picking up quite a lot of noise  on the microphones when using WiFi. To fix this noise problem we are creating a  clean 3.3v power supply for the microphones   we do this by taking a direct feed from the battery,  we filter this with an LC filter and then   pass this to a Low Drop Out regulator.  This gives us a really nice and clean   power supply for the microphones which  removes a lot of the noise issues. I've got quite a few videos on audio  input and output which you might find   interesting - I've linked to  the playlist in the description. That's really all there is on  the hardware side of things. How does it actually work? All the code is on GitHub - the link  is in the description - it should be   mostly self-explanatory, but I'll  give a high-level overview here. The main challenge with this project   is how to get the audio broadcast from one  walkie-talkie to all the other walkie-talkies. I've implemented this in two different ways. You   can easily switch between these in  the code with a simple #define. The first way is using UDP broadcast.   UDP broadcast is a very simple mechanism. You  send a UDP packet to a special IP address and   your router broadcasts this packet to  all the other devices on your network. We can safely send up to  1436 bytes in a UDP packet   so if we're sampling at 16KHz and using 8-bit  samples that's around 90ms of audio data.   So we need to send around 11 packets per second.  This is well within the capabilities of the ESP32. The big advantage of using broadcast UDP is  that we don't need to know about our peers,   we can just broadcast a message and anyone who is  listening for it will receive it. We also don't   need a centralised server that everything connects  to. All the heavy lifting is done by the router. However, there are some disadvantages  of UDP that we should be aware of. Delivery of UDP packets is  only best effort - there is   no guarantee that someone will  receive the packet you send. There is also no guarantee  of packet ordering - someone   may receive the packets you have  sent in a completely random order. For this project, I've chosen  to ignore these two issues.   With broadcast packets, we're  generally staying in the same network   so we probably won't lose too many packets  and our packets will probably also come in   the correct order. If they don't then we'll just  get a bit of noise and distortion on the audio. The other big advantage of UDP  broadcast is that you can receive   the packets on your desktop computer  or even your phone - so it would be quite   easy to create additional clients  that are not based on the ESP32. The second way I've implemented  the transport is to use ESP-NOW. ESP-NOW is a protocol developed by  Esppresif which enables multiple   ESP devices to communicate with  each other without needing WiFi. This gives us one great  advantage over the UDP option   in that we don't need a WiFi network  to make our Walkie-Talkie work. So you could use the Walkie-Talkie outside. The disadvantage with ESP-NOW is that it  has a much smaller packet size of 250 bytes.   This means that we need to be  sending packets 64 times a second. We also have all the same downsides as  UDP broadcast - packet delivery is best effort   and there is no guarantee what  order the packets will arrive in. However, in my tests, it seems to have  performed reasonably well. With the transport problem solved  we just need to hook everything up. We have the I2S input - this reads samples from  the microphone and passes them to our transport. Once the transport has accumulated  enough data to fill a packet   it sends the data through either UDP or ESP-NOW. On the other side, we have the same  transport listening for packets.   Every time a packet is received  it queues the data up for playing   via our I2S output. The I2S output just  pushes samples out to the I2S amplifier. To allow for packets taking slightly  longer to arrive we have a buffer   between the transport and the I2S output.  We let a small amount of time elapse before   we start playing the samples - this gives us  some spare time to allow for packet jitter.   It does come at the cost of some latency in the  audio - with everything taken into account using UDP the   audio is played about half  a second after it was made. All in all though the project works. Quality is not amazing,   but it's certainly sufficient for a hobby project. And sounds like a fairly low-quality Walkie-Talkie As always, the code is all on GitHub. Let  me know what you think in the comments.   And if you have any improvements  then please open up a pull request. Some ideas that would be good to look at: Compression of the audio to reduce bandwidth. Some kind of Automatic Gain Control Echo cancellation so we can have full-duplex And I'm sure there's much much more that can be improved. So feel free to hack away! So that's it for this video. I hope you enjoyed it. I certainly enjoyed making it. And if you did enjoy it please hit the subscribe button. There are more videos coming soon. So I'll see you in the next video!

Channel: atomic14

Views: 27,089

Keywords: ESP32, ESP32 Project, Walkie-talkie, walky-talky, I2S, Audio, DAC, ADC, UDP Broadcast, ESP-NOW, esp-now tutorial, esp32 projects, esp now, esp32 walkie talkie

Id: d_h38X4_eQQ

Length: 8min 50sec (530 seconds)

Published: Mon Apr 05 2021

Reddit Comments

[u/iamflimflam1]

This was a fun project - I've managed to get it working over both UDP broadcast and ESP-NOW so it will work either with or without a WiFi network.

Code is all here: https://github.com/atomic14/esp32-walkie-talkie

[u/shantired]

For range: I've probably mentioned this before, but one of my antenna designers was able to get 1200' line of sight using a rubber ducky antenna. This was the best range, and the worst range was about 700' line of sight.

This was without using antenna diversity. If you enable antenna diversity (2 antennas - polarize the antennas orthogonal to each other), and use GPIO0 or GPIO1 for switch control, you may get even better range. Diversity is built-into the API. In our case, for our application, a solid uniform pattern was more important than range so we used diversity, so we designed efficient antennas to have complimentary nulls.

[u/Random_182f2565]

Thank you so much I love Walkie-Talkies, what is the effective range?