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ESP Mesh Network with OSC

2020-03-23 19:32:13 electronics

With the painlessMesh library, it turned out easy to set up a decentralised mesh network for a few ESP8266 modules. The example below shows how I set it up and how to send and receive OpenSoundControl (OSC) messages. The code also works on an ESP32.

  1. Install the painlessMesh and the OSC libraries for Arduino.
  2. Program a few nodes (ESP8266) so that they all run this code...
//req. libraries: OSC, painlessMesh

#include <Arduino.h>
#include <painlessMesh.h>
#include <WiFiUdp.h>
#include <OSCMessage.h>
#include <OSCData.h>

#define MESH_NAME "networkname" //EDIT mesh name
#define MESH_PASS "networkpass" //EDIT password
#define MAX_CONN 4 //EDIT ESP32 can have more than ESP8266

#define INPORT 19998 //OSC in port
#define OUTPORT 57120 //OSC out port (SC)

IPAddress outIP;
WiFiUDP Udp;
painlessMesh mesh;

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  mesh.init(MESH_NAME, MESH_PASS, 5555, WIFI_AP_STA, 1, 0, MAX_CONN);
  Udp.begin(INPORT);
}

void pingFunc(OSCMessage &inMsg) {
  digitalWrite(LED_BUILTIN, 1 - digitalRead(LED_BUILTIN));  //toggle led
  OSCMessage outmsg("/pong");
  outmsg.add(mesh.getNodeId()); //uint32
  IPAddress ip;
  ip= mesh.getStationIP(); //0.0.0.0 if current base station
  outmsg.add(ip[0]);
  outmsg.add(ip[1]);
  outmsg.add(ip[2]);
  outmsg.add(ip[3]);
  ip= mesh.getAPIP();
  outmsg.add(ip[0]);
  outmsg.add(ip[1]);
  outmsg.add(ip[2]);
  outmsg.add(ip[3]);
  Udp.beginPacket(outIP, OUTPORT);
  outmsg.send(Udp);
  Udp.endPacket();
}

void loop() {
  mesh.update();

  int packetSize= Udp.parsePacket();
  if (packetSize) {
    OSCMessage inMsg;
    while (packetSize--) {
      inMsg.fill(Udp.read());
    }
    if (!inMsg.hasError()) {
      outIP= Udp.remoteIP();
      inMsg.dispatch("/ping", pingFunc);
    }
  }
}
  1. After that power up the nodes and a new WiFi network should show up.
  2. Connect a laptop to the new mesh network and take note of the IP number assigned.
  3. Run the test code below on the laptop. It will broadcast a \ping OSC message and listen for \pong replies.

The test code is for SuperCollider but any program that can send OSC should work.

(
OSCFunc({|msg| msg.postln}, \pong);
NetAddr.broadcastFlag= true;
NetAddr("10.214.190.255", 19998).sendMsg(\ping);  //EDIT laptop ip number but leave 255 as the last number
)

The painlessMesh library will for sure come in handy when I need a network without a WiFi router, or for when trying to cover a larger area.

A major drawback though seems to be that the maximum number of nodes that can be used is really low. Apparently, an ESP8266 can only handle 5 (TCP/IP) connections at the same time and an ESP32 about three times that. And that is not very many.

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