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Getting error after using extern #4
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Hi @khoih-prog, Thank you for developing an excellent library. I have been trying to develop multi cpp project in platformio and whenever I define "AsyncMqttClient" class object with the "extern" in defines.h and declare it in main.cpp I am getting scarry looking error "...: first defined here" But when I use "AsyncMqttClient" library instead I am not getting any error. Can you help in this regard? main.cpp:#include "defines.h"
const char *PubTopic = "async-mqtt/ESP32_Pub"; // Topic to publish
AsyncMqttClient mqttClient;
TimerHandle_t mqttReconnectTimer;
TimerHandle_t wifiReconnectTimer;
void connectToWifi()
{
Serial.println("Connecting to Wi-Fi...");
WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
}
void connectToMqtt()
{
Serial.println("Connecting to MQTT...");
mqttClient.connect();
}
void WiFiEvent(WiFiEvent_t event)
{
switch (event)
{
#if USING_CORE_ESP32_CORE_V200_PLUS
case ARDUINO_EVENT_WIFI_READY:
Serial.println("WiFi ready");
break;
case ARDUINO_EVENT_WIFI_STA_START:
Serial.println("WiFi STA starting");
break;
case ARDUINO_EVENT_WIFI_STA_CONNECTED:
Serial.println("WiFi STA connected");
break;
case ARDUINO_EVENT_WIFI_STA_GOT_IP6:
case ARDUINO_EVENT_WIFI_STA_GOT_IP:
Serial.println("WiFi connected");
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
connectToMqtt();
break;
case ARDUINO_EVENT_WIFI_STA_LOST_IP:
Serial.println("WiFi lost IP");
break;
case ARDUINO_EVENT_WIFI_STA_DISCONNECTED:
Serial.println("WiFi lost connection");
xTimerStop(mqttReconnectTimer, 0); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
xTimerStart(wifiReconnectTimer, 0);
break;
#else
case SYSTEM_EVENT_STA_GOT_IP:
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
connectToMqtt();
break;
case SYSTEM_EVENT_STA_DISCONNECTED:
Serial.println("WiFi lost connection");
xTimerStop(mqttReconnectTimer, 0); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
xTimerStart(wifiReconnectTimer, 0);
break;
#endif
default:
break;
}
}
void printSeparationLine()
{
Serial.println("************************************************");
}
void onMqttConnect(bool sessionPresent)
{
Serial.print("Connected to MQTT broker: ");
Serial.print(MQTT_HOST);
Serial.print(", port: ");
Serial.println(MQTT_PORT);
Serial.print("PubTopic: ");
Serial.println(PubTopic);
printSeparationLine();
Serial.print("Session present: ");
Serial.println(sessionPresent);
uint16_t packetIdSub = mqttClient.subscribe(PubTopic, 2);
Serial.print("Subscribing at QoS 2, packetId: ");
Serial.println(packetIdSub);
mqttClient.publish(PubTopic, 0, true, "ESP32 Test");
Serial.println("Publishing at QoS 0");
uint16_t packetIdPub1 = mqttClient.publish(PubTopic, 1, true, "test 2");
Serial.print("Publishing at QoS 1, packetId: ");
Serial.println(packetIdPub1);
uint16_t packetIdPub2 = mqttClient.publish(PubTopic, 2, true, "test 3");
Serial.print("Publishing at QoS 2, packetId: ");
Serial.println(packetIdPub2);
printSeparationLine();
}
void onMqttDisconnect(AsyncMqttClientDisconnectReason reason)
{
(void)reason;
Serial.println("Disconnected from MQTT.");
if (WiFi.isConnected())
{
xTimerStart(mqttReconnectTimer, 0);
}
}
void onMqttSubscribe(const uint16_t &packetId, const uint8_t &qos)
{
Serial.println("Subscribe acknowledged.");
Serial.print(" packetId: ");
Serial.println(packetId);
Serial.print(" qos: ");
Serial.println(qos);
}
void onMqttUnsubscribe(const uint16_t &packetId)
{
Serial.println("Unsubscribe acknowledged.");
Serial.print(" packetId: ");
Serial.println(packetId);
}
void onMqttMessage(char *topic, char *payload, const AsyncMqttClientMessageProperties &properties,
const size_t &len, const size_t &index, const size_t &total)
{
(void)payload;
Serial.println("Publish received.");
Serial.print(" topic: ");
Serial.println(topic);
Serial.print(" qos: ");
Serial.println(properties.qos);
Serial.print(" dup: ");
Serial.println(properties.dup);
Serial.print(" retain: ");
Serial.println(properties.retain);
Serial.print(" len: ");
Serial.println(len);
Serial.print(" index: ");
Serial.println(index);
Serial.print(" total: ");
Serial.println(total);
}
void onMqttPublish(const uint16_t &packetId)
{
Serial.println("Publish acknowledged.");
Serial.print(" packetId: ");
Serial.println(packetId);
}
void setup()
{
Serial.begin(115200);
while (!Serial && millis() < 5000)
;
delay(500);
Serial.print("\nStarting FullyFeature_ESP32 on ");
Serial.println(ARDUINO_BOARD);
Serial.println(ASYNC_MQTT_ESP32_VERSION);
mqttReconnectTimer = xTimerCreate("mqttTimer", pdMS_TO_TICKS(2000), pdFALSE, (void *)0,
reinterpret_cast<TimerCallbackFunction_t>(connectToMqtt));
wifiReconnectTimer = xTimerCreate("wifiTimer", pdMS_TO_TICKS(2000), pdFALSE, (void *)0,
reinterpret_cast<TimerCallbackFunction_t>(connectToWifi));
WiFi.onEvent(WiFiEvent);
mqttClient.onConnect(onMqttConnect);
mqttClient.onDisconnect(onMqttDisconnect);
mqttClient.onSubscribe(onMqttSubscribe);
mqttClient.onUnsubscribe(onMqttUnsubscribe);
mqttClient.onMessage(onMqttMessage);
mqttClient.onPublish(onMqttPublish);
test();
connectToWifi();
}
void loop()
{
}defines.h:/****************************************************************************************************************************
defines.h
AsyncMQTT_ESP32 is a library for ESP32 boards using WiFi or LwIP W5500, LAN8720 or ENC28J60
Based on and modified from :
1) async-mqtt-client (https://github.com/marvinroger/async-mqtt-client)
2) async-mqtt-client (https://github.com/khoih-prog/AsyncMQTT_Generic)
Built by Khoi Hoang https://github.com/khoih-prog/AsyncMQTT_ESP32
***************************************************************************************************************************************/
#ifndef defines_h
#define defines_h
#define _ASYNC_MQTT_LOGLEVEL_ 1
#include <Arduino.h>
#include <WiFi.h>
#include <AsyncMQTT_ESP32.h>
#include <Test.h>
extern "C"
{
#include "freertos/FreeRTOS.h"
#include "freertos/timers.h"
}
extern AsyncMqttClient mqttClient;
extern TimerHandle_t mqttReconnectTimer;
extern TimerHandle_t wifiReconnectTimer;
//#define MQTT_HOST IPAddress(192, 168, 2, 110)
#define MQTT_HOST "broker.emqx.io" // Broker address
#define MQTT_PORT 1883
#define WIFI_SSID "Digisol"
#define WIFI_PASSWORD "12345678"
#endif //defines_hTest.h:#ifndef Test_H
#define Test_H
void test();
#endifTest.cpp:#include "defines.h"
void test()
{
mqttClient.setServer(MQTT_HOST, MQTT_PORT);
}Error: |
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Answered by
khoih-prog
Jan 11, 2023
Replies: 3 comments 1 reply
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Hi @otl1 Thanks for your encouraging words. The real reason is that I'm using the better
I'm sorry that I haven't included the similar section in this library. From the above explanation, you can see in your original code, the
To fix your code, just modify a little bit as follows: main.cpp:#include "defines.h"
#include <AsyncMQTT_ESP32.h>
const char *PubTopic = "async-mqtt/ESP32_Pub"; // Topic to publish
...defines.h:/****************************************************************************************************************************
defines.h
AsyncMQTT_ESP32 is a library for ESP32 boards using WiFi or LwIP W5500, LAN8720 or ENC28J60
Based on and modified from :
1) async-mqtt-client (https://github.com/marvinroger/async-mqtt-client)
2) async-mqtt-client (https://github.com/khoih-prog/AsyncMQTT_Generic)
Built by Khoi Hoang https://github.com/khoih-prog/AsyncMQTT_ESP32
***************************************************************************************************************************************/
#ifndef defines_h
#define defines_h
#define _ASYNC_MQTT_LOGLEVEL_ 1
#include <Arduino.h>
#include <WiFi.h>
//#include <AsyncMQTT_ESP32.h>
#include <AsyncMQTT_ESP32.hpp>
//#include <Test.h>
#include "Test.h"
... |
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1 reply
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Thanks, @khoih-prog for the quick response. Keep up the good work! |
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Answer selected by
otl1
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Hello @khoih-prog When I include |
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0 replies
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Check Global declaration of object of "ESPAsyncWebServer" causing conflict #5 |
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Hi @otl1
Thanks for your encouraging words.
The real reason is that I'm using the better
h-onlystyle for many of my libraries. To avoidMultiple Definitions Linker Error, we have to follow instructions in HOWTO Fix Multiple Definitions Linker Error and the example multiFileProject*.hfile must be included only once, for example inmain.cppor main.inofiles*.hppfile can be included as many times as necessary, withoutMultiple DefinitionsLinker ErrorI'm sorry that I haven't included the similar section in this library.
From the above explanation, you can see in your original code, the
AsyncMQTT_ESP32.hhas been included indefines.handTest.hviadefines.hTo fix your …