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Vigibot Pi to multiple ESP32 WLAN Communications Example

esp32 arduino

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#1 firened

firened

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Posté 15 décembre 2020 - 11:11

UPDATE 16.08.2021: find the updated code and guide on GitHub: https://github.com/e...-Multiple-ESP32

Note:
if you want to control a single ESP32 robot/gadget, use this guide instead:
https://www.robot-ma...ample/?p=111377
if you want to control multiple ESP32 robots/gadgets, continue.

This code allows control of multiple ESP32 robots or gadgets over WLAN using vigibot.
A raspberry is still required for the camera and needs to be on the same network. the serial data usually sent and received to an Arduino over UART ( https://www.robot-ma...cation-example/ ), is being sent over WLAN instead, allowing control of small robots or gadgets.
usage example: a pi with a camera watches an arena where multiple small ESP32 robots can be driven, the ESP32 bots do not have an on-board camera.
second usage example: open or close a door or toy controlled fron an ESP32.

1) assign your pi a static IP address
https://thepihut.com...-address-update

2) the pi needs to create a virtual serial point that's accessible over WLAN from the ESP32. install socat and ncat on your raspberry:
sudo apt install socat ncat
3) create a new script:
sudo nano /usr/local/ncat_esp.sh
4) paste the following code:
#!/bin/bash

sudo socat pty,link=/dev/ttyVigi0,rawer,shut-none pty,link=/dev/ttySrv,rawer,shut-none &

while true
do
  sleep 1
  sudo ncat -l -k -4 --idle-timeout 15 7070 </dev/ttySrv >/dev/ttySrv
  date
  echo "restarting ncat"
done
5) add permissions
sudo chmod +x /usr/local/ncat_esp.sh
6) run the script
sudo /usr/local/ncat_esp.sh
7) insert your
- network info
- raspberry host IP
- vigibot NBpositions (if different from default)
into the following sketch and upload it to your ESP32 from the arduino IDE using a usb cable.
note: only one esp can send a reply, make sure `client.write();` is only being called on one ESP32, all others only listen without sending any data back. (i recommend that one ESP32 sends data back, this way the vigibot robot won't wake up if the ESP32 isn't connected properly, which makes it easier to notice that it isn't working.)

Spoiler


8) open the serial monitor to confirm a successful WLAN and TCP client connection.

9) test the pi <-> ESP connection by logging in as root in a new shell (needs root) :
su -
and sending a test text frame:
echo '$T  hello from cli       $n' > /dev/ttyVigi0
the arduino serial monitor now says "hello from cli "

10)if it works add it to start at boot:
sudo nano /etc/rc.local
and add
/usr/local/socat-esp.sh &
above the line "exit 0".

11) add an entry on the vigibot online remote control config -> SERIALPORTS -> 3 with value: "/dev/ttyVigi0"

12) set WRITEUSERDEVICE to "3"

13) if you set up an ESP32 to send data back:
set READUSERDEVICE to "3"

restart the client and wake your robot up, if it wakes up then everything works.


related notes:
you can add a dummy client from the command line, in case you want to check if the vigibot frames are made available:   
sudo socat tcp:localhost:7070 -
   

similarly it's theoretically also possible to fetch this data from another computer or custom script/application.

there's an outage happening every few weeks or so, from which it doesn't recover.   
it looks like ncat doesn't open the socat socket if there's too much data buffered. the workaround is to manually clear the socat socket using
sudo cat /dev/ttySrv
and then cancel with `ctrl-c`

 

#2 zavatha

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Posté 16 décembre 2020 - 10:59

Salut à tous,

 

J'avais dans l'idée de d'utiliser vigibot pour contrôler un projet à base d'ESPCam 32...

Le but étant de streamer non pas la video de la cam du pi mais celle de l'ESP cam... quitte à utiliser le PI comme passerelle et que ce soit lui qui s'ovvupe de commuter à video à consulter à la demande... un vigibot dans vigibot en somme :P

 

Je n'ai pas encore creusé... acr je n'ai le temps de rien, quasiment tous les projets sont en pause depuis 2 mois...

 

est-ce possible ?... en tout cas avec ce poste on s'en approche ;)

 

L'idée serait de contrôler plusieurs devices lowcost constitués sur la même base et de passer de l'un à l'autre...

 

allez je balance un screenshot de la modélisation du projet en question (le proto du premier device), l'électronique est en cours d'assemblage / tests et le dev (V1) est fait à 90% : 

 

image_2020-12-16_105220.png

 

pour le moment, le device heberge un serveur web et est donc contrôlé en direct avec un smartphone...

 

@+

 

Zav



#3 firened

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Posté 16 décembre 2020 - 11:12

Hi Zav
i thought about that too, it would be cool.
i doubt an esp32 will be able to send a low latency video stream. i don't know though, haven't used a cam32 board yet.

a different option could be using an analog fpv cam like a runcam used on multicopters and send that video to a usb capture device on a raspberry pi.
fpv cameras can have a very small footprint, which is great for tiny robots where a pi doesn't fit onto.

is your cam 32 webview test already working? I'd love to hear about its latency, resolution and fps rate.

good luck

#4 zavatha

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Posté 16 décembre 2020 - 11:31

hi firened,

 

i don't have analog runcam because of low costs constraints... so i turned back to espcam 32 (6$ only)

i agree : low latency streaming is a little bit deception with espcam 32 so for the moment i only make one POOC and i will see the effectivity of the system...

i didnt made serious mesures but i think i have 5fps, perhaps 10fps with correct resolution (not 320p)

it is not very good but sufficient for my usage...

 

but, in an other hand, i observed stability issues (freeze) while connected to my computer with a ftdi module... wait to see with dedicated power supply system.

 

i totaly agree with you and think a realist way is to use some fpv cams, associated to esp in order pilot the devices from the PI... like Pascal conception for vigibot... but don't have the funds :(

 

have a good day

 

@+

Zav





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