I'm new to WiShelid and trying to get MQTT , the pub/sub communication protocol from Andy Stanford-Clark and friends, working on an arduino. (see http://knolleary.net/arduino-client-for-mqtt/, I'm trying to figure out how to adapt it for the WiShield . I tried just adding #include <WiServer.h> but that wouldn't compile with the Ethernet.h header because of conflicting var definitions. I started to try and debug and modify the headers but soon realized this would get complicated. Before I spend more time on it has anyone
- already got WiSheld working with MQTT ?
- know what I'd have to hack in the PubSubClient function to substitute WiSheld TCPIP open/close etc for the Ethernet.h specific stuff that's already there ?
Any help appreciated .. Happy new year everyone !
-jc
Here's the MQTT test sketch from http://knolleary.net/arduino-client-for-mqtt/
- Code: Select all
#include <Ethernet.h>
#include <PubSubClient.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 172, 16, 0, 1 };
byte server[] = { 172, 16, 0, 100 };
void callback(char* topic, byte* payload,int length) {
// handle message arrived
}
PubSubClient client(server, 1883, callback);
void setup()
{
Ethernet.begin(mac, ip);
if (client.connect("arduino")) {
client.publish("foo","hello world");
client.subscribe("bar");
}
}
void loop()
{
client.loop();
}
Here's the PubSubClient.cpp from http://knolleary.net/arduino-client-for-mqtt/
- Code: Select all
/*
PubSubClient.cpp - A simple client for MQTT.
Nicholas O'Leary
http://knolleary.net
*/
#include "WConstants.h"
#include "PubSubClient.h"
#include "Client.h"
#include "string.h"
#define MQTTCONNECT 1<<4
#define MQTTPUBLISH 3<<4
#define MQTTSUBSCRIBE 8<<4
PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, void (*callback)(char*,uint8_t*,int)) : _client(ip,port) {
this->callback = callback;
}
int PubSubClient::connect(char *id) {
return connect(id,0,0,0,0);
}
int PubSubClient::connect(char *id, char* willTopic, uint8_t willQos, uint8_t willRetain, char* willMessage) {
if (!_client.connected()) {
if (_client.connect()) {
nextMsgId = 1;
uint8_t d[9] = {0x00,0x06,0x4d,0x51,0x49,0x73,0x64,0x70,0x03};
uint8_t length = 0;
int j;
for (j = 0;j<9;j++) {
buffer[length++] = d[j];
}
if (willTopic) {
buffer[length++] = 0x06|(willQos<<3)|(willRetain<<5);
} else {
buffer[length++] = 0x02;
}
buffer[length++] = 0;
buffer[length++] = (KEEPALIVE/500);
length = writeString(id,buffer,length);
if (willTopic) {
length = writeString(willTopic,buffer,length);
length = writeString(willMessage,buffer,length);
}
write(MQTTCONNECT,buffer,length);
while (!_client.available()) {}
uint8_t len = readPacket();
if (len == 4 && buffer[3] == 0) {
lastActivity = millis();
return 1;
}
_client.stop();
}
}
return 0;
}
uint8_t PubSubClient::readPacket() {
uint8_t len = 0;
buffer[len++] = _client.read();
uint8_t multiplier = 1;
uint8_t length = 0;
uint8_t digit = 0;
do {
digit = _client.read();
buffer[len++] = digit;
length += (digit & 127) * multiplier;
multiplier *= 128;
} while ((digit & 128) != 0);
for (int i = 0;i<length;i++)
{
if (len < MAX_PACKET_SIZE) {
buffer[len++] = _client.read();
} else {
_client.read();
len = 0; // This will cause the packet to be ignored.
}
}
return len;
}
int PubSubClient::loop() {
if (_client.connected()) {
long t = millis();
if (t - lastActivity > KEEPALIVE) {
_client.write(192);
_client.write((uint8_t)0);
lastActivity = t;
}
if (_client.available()) {
uint8_t len = readPacket();
if (len > 0) {
uint8_t type = buffer[0]>>4;
if (type == 3) { // PUBLISH
if (callback) {
uint8_t tl = (buffer[2]<<3)+buffer[3];
char topic[tl+1];
for (int i=0;i<tl;i++) {
topic[i] = buffer[4+i];
}
topic[tl] = 0;
// ignore msgID - only support QoS 0 subs
uint8_t *payload = buffer+4+tl;
callback(topic,payload,len-4-tl);
}
} else if (type == 12) { // PINGREG
_client.write(208);
_client.write((uint8_t)0);
lastActivity = t;
}
}
}
return 1;
}
return 0;
}
int PubSubClient::publish(char* topic, char* payload) {
return publish(topic,(uint8_t*)payload,strlen(payload));
}
int PubSubClient::publish(char* topic, uint8_t* payload, uint8_t plength) {
if (_client.connected()) {
uint8_t length = writeString(topic,buffer,0);
int i;
for (i=0;i<plength;i++) {
buffer[length++] = payload[i];
}
//header |= 1; retain
write(MQTTPUBLISH,buffer,length);
return 1;
}
return 0;
}
int PubSubClient::write(uint8_t header, uint8_t* buf, uint8_t length) {
_client.write(header);
_client.write(length);
for (int i=0;i<length;i++) {
_client.write(buf[i]);
}
return 0;
}
void PubSubClient::subscribe(char* topic) {
if (_client.connected()) {
uint8_t length = 2;
nextMsgId++;
buffer[0] = nextMsgId >> 8;
buffer[1] = nextMsgId - (buffer[0]<<8);
length = writeString(topic, buffer,length);
buffer[length++] = 0; // Only do QoS 0 subs
write(MQTTSUBSCRIBE,buffer,length);
}
}
void PubSubClient::disconnect() {
_client.write(224);
_client.write((uint8_t)0);
_client.stop();
lastActivity = millis();
}
uint8_t PubSubClient::writeString(char* string, uint8_t* buf, uint8_t pos) {
char* idp = string;
uint8_t i = 0;
pos += 2;
while (*idp) {
buf[pos++] = *idp++;
i++;
}
buf[pos-i-2] = 0;
buf[pos-i-1] = i;
return pos;
}
int PubSubClient::connected() {
return (int)_client.connected();
}
and here's the PubSubClient.h from http://knolleary.net/arduino-client-for-mqtt/
- Code: Select all
/*
PubSubClient.h - A simple client for MQTT.
Nicholas O'Leary
http://knolleary.net
*/
#ifndef PubSubClient_h
#define PubSubClient_h
#include "Client.h"
#define MAX_PACKET_SIZE 128
#define KEEPALIVE 15000 // max value = 255000
class PubSubClient {
private:
Client _client;
uint8_t buffer[MAX_PACKET_SIZE];
uint8_t nextMsgId;
long lastActivity;
void (*callback)(char*,uint8_t*,int);
uint8_t readPacket();
int write(uint8_t header, uint8_t* buf, uint8_t length);
uint8_t writeString(char* string, uint8_t* buf, uint8_t pos);
public:
PubSubClient(uint8_t *, uint16_t, void(*)(char*,uint8_t*,int));
int connect(char *);
int connect(char*, char*, uint8_t, uint8_t, char*);
void disconnect();
int publish(char *, char *);
int publish(char *, uint8_t *, uint8_t);
void subscribe(char *);
int loop();
int connected();
};
#endif
