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Enable and disable I/O of a M-Duino with UDP
Introduction
In this post will be shown an application of using a UDP connection between PC and M-DUINO. The aim is enable and disable Inputs and Outputs with a message.
Requirements
Ethernet2 library provided by Industrial Shields. Downloading our boards you will have this library. In this link you can read the blog where it explains how to get it.
Application
With Ethernet2.h we also have available EthernetUDP2.h. This library allows you to send and receive messages with UDP.
First of all we have to create your local network to work better without disturbing anyone. Here you have an example diagram:
Our M-Duino has be:ad:be:ef:fe:ed as address mac, 10.20.1.2 as IP and 8888 as local port. The steps to follow are:
- Configurate our M-Duino with these parameters.
- Waiting for a message to be received.
- Transmit confirmation message.
- Analyze the message.
Reception
Messages Protocol
There are different ways to send the messages, it's up to you, but in our case we have used the next protocol:
ON:QX.X to enable a relay
OFF:QX.X to disable a relay
Knowing the structure of the message that we will receive allows us to know how to filter/analyze it to enable or disable the desired input/output. In this example we enable and disable a Digital output, but can be applied to an Analog Input/Output or Relay Output using the same protocol. As we know the structure of the messages we can filter by types, Q -> Digital, A -> Analog, R -> Relay...and enable or disable the pin according to the entrance: ON or OFF.
Transmission
Once we have received a message, we send a confirmation message, ACK, to the remote IP. The port used to transmit the message is 5566.
Code
This code is prepared for a M-Duino 21+, so we have use Digital I/O (Q0.0...Q0.7). However, as you can see, if you use other boards where there are more zones or have relays, you only have to add the necessary code to filter correctly.
Here you have the code:
#include <Ethernet2.h>
#include <EthernetUdp2.h>
byte mac[] = { 0xBE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip(10, 20, 1, 2);
uint16_t rx_udp_port = 8888; // local port to listen on
uint16_t tx_udp_port = 5566;
char packetBuffer[UDP_TX_PACKET_MAX_SIZE];
char *replyBuffer = "ACK\n"; // acknoleged;
EthernetUDP Udp;
void setup() {
// start Ethernet
Serial.begin(9600);
Ethernet.begin(mac, ip);
Serial.println(Ethernet.localIP());
// start UDP
Udp.begin(rx_udp_port);
}
static void filter_message(char *packet){
char zone, pin;
switch(packet[1]){
case 'N': // Filter by N -> ON
if (packet[3] == 'Q'){ // Filter by Q -> Digital pin
zone = packet[4];
pin = packet[6];
if (zone == '0'){ // Filter by zone 0, 1 or 2
switch(pin){ // Filter by pin 0, 1, 2, 3, 4, 5, 6 or 7
case '0':
digitalWrite(Q0_0, HIGH);
break;
case '1':
digitalWrite(Q0_1, HIGH);
break;
case '2':
digitalWrite(Q0_2, HIGH);
break;
case '3':
digitalWrite(Q0_3, HIGH);
break;
case '4':
digitalWrite(Q0_4, HIGH);
break;
case '5':
digitalWrite(Q0_5, HIGH);
break;
case '6':
digitalWrite(Q0_6, HIGH);
break;
case '7':
digitalWrite(Q0_7, HIGH);
break;
}
}/* If it had more zones
else if (zone == '1'){
switch(pin){
case '1':
digitalWrite(Q1_0, HIGH);
break;
case '2':
digitalWrite(Q1_1, HIGH);
break;
case '3':
digitalWrite(Q1_2, HIGH);
break;
.
.
.
}
}
else if (zone == '2'){
switch(pin){
case '1':
digitalWrite(Q2_0, HIGH);
break;
case '2':
digitalWrite(Q2_1, HIGH);
break;
case '3':
digitalWrite(Q2_2, HIGH);
break;
.
.
.
}
}*/
Serial.print("Digital ");
Serial.print(zone);
Serial.print(".");
Serial.print(pin);
Serial.println(" activated");
}
break;
case 'F': // Filter by F -> OFF
if (packet[4] == 'Q'){ // some relay I/O
zone = packet[5];
pin = packet[7];
if (zone == '0'){
switch(pin){
case '0':
digitalWrite(Q0_0, LOW);
break;
case '1':
digitalWrite(Q0_1, LOW);
break;
case '2':
digitalWrite(Q0_2, LOW);
break;
case '3':
digitalWrite(Q0_3, LOW);
break;
case '4':
digitalWrite(Q0_4, LOW);
break;
case '5':
digitalWrite(Q0_5, LOW);
break;
case '6':
digitalWrite(Q0_6, LOW);
break;
case '7':
digitalWrite(Q0_7, LOW);
break;
}
}/*
else if (zone == '1'){
switch(pin){
case '1':
digitalWrite(Q1_0, LOW);
break;
case '2':
digitalWrite(Q1_1, LOW);
break;
case '3':
digitalWrite(Q1_2, LOW);
break;
.
.
.
}
}
else if (zone == '2'){
switch(pin){
case '1':
digitalWrite(Q2_0, LOW);
break;
case '2':
digitalWrite(Q2_1, LOW);
break;
case '3':
digitalWrite(Q2_2, LOW);
break;
.
.
.
}
}*/
Serial.print("Digital ");
Serial.print(zone);
Serial.print(".");
Serial.print(pin);
Serial.println(" desactivated");
}
break;
}
}
void loop() {
int packetSize = Udp.parsePacket();
if (packetSize) {
// read the packet into packetBufffer
Udp.read(packetBuffer, UDP_TX_PACKET_MAX_SIZE);
// send a reply to the IP address and port that sent us the packet we received
Udp.beginPacket(Udp.remoteIP(), tx_udp_port);
Udp.write(replyBuffer);
Udp.endPacket();
filter_message(packetBuffer);
}
delay(10);
}Demostration
In this demostration we send four messages from the PC (IP : 10.20.1.1) to the M-Duino (IP : 10.20.1.2)
Message 1: Enable Digital pin 0.1
Message 2: Enable Digital pin 0.5
Message 3: Disable Digital pin 0.1
Message 4: Disable Digital pin 0.5
The following image shows this
