Description
Few days ago, I posted this question in Arduino stackExchange- but no one answered.
I'll be happy to help and get help
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Problem description: Every ~20+ published messages (using terminal), MCU receives that message in a very noticeable delay (mostly ~10 sec, few time it got up to 1 min). Upon receive (printed in Serial monitor), MCU is working as expected.
Hardware: ESP32 DEVKIT MCU, PubSubClient.h for MQTT and WiFi.h for WiFi.
Important remark: Code is same for ESP8266 and ESP32.This behavior happens only on ESP32.
Question: Does ESP32 has a know issue regarding receiving MQTT messages? is there a workaround? or perhaps- bug in code?
What did I do to try isolating the problem:
-
Tried on 3 different ESP32s (2 DEVkit MCU, and 1 with relays on board) - same behavior - it is not an specific MCU hardware problem.
-
Used another PC to publish MQTT messages (via terminal. MAC and Linux, and a 3rd party MQTT App)- no change. It has nothing to do with publishing platform.
-
To rule out it may be a MQTT broker's fault (Local RPI3 connected using LAN cable)- Subscribing to that topic in order to see if the delay repeats . MQTT server receive pubs on time. Broker responds on time (while waiting to see when publish is received in Serial monitor).
-
adding a flashing LED every 200ms in
loop(), to verify that MCU is not get stuck in a process.loop()is looping as expected (see in code below). -
Spitting heap free memory to Serial monitor, in order to see if there is some memory issue, degradation. Nothing suspicious.
-
Code simplification- used code segments from ESP32 wifi and MQTT pubsub's example, while disabling every functionality of original code(with and without). Delay still happens sporadically.
OUTPUT1- sending "0" and "1" almost simultaneously, almost 15 sec delay
13:31:21.516 -> Message arrived [myHome/test] 0 <--- right after this, "1" was sent
13:31:22.510 -> 278616 <---- free heap size (send every 1000 ms. non-blocking)
13:31:23.570 -> 278616
13:31:24.630 -> 278616
13:31:25.657 -> 278616
13:31:26.718 -> 278616
13:31:27.778 -> 278616
13:31:28.805 -> 278616
13:31:29.866 -> 278616
13:31:30.926 -> 278616
13:31:31.954 -> 278616
13:31:33.014 -> 278616
13:31:34.075 -> 278616
13:31:35.102 -> 278616
13:31:35.964 -> Message arrived [myHome/test] 1 <--- received 15 sec later
OUTPUT-2: Code
#include <WiFi.h>
#include <PubSubClient.h>
WiFiClient espClient;
PubSubClient client(espClient);
const char *mqtt_server = "192.168.2.100";
void setup_wifi()
{
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
// Serial.println(ssid);
WiFi.mode(WIFI_STA);
WiFi.begin("iot", "GdS");
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void callback(char *topic, byte *payload, unsigned int length)
{
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++)
{
Serial.print((char)payload[i]);
}
Serial.println();
// Switch on the LED if an 1 was received as first character
}
void reconnect()
{
// Loop until we're reconnected
while (!client.connected())
{
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "ESP8266Client-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str()),"guy","kupelu9e")
{
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("myHome/log", "hello world");
// ... and resubscribe
client.subscribe("myHome/test");
}
else
{
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup()
{
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
reconnect();
}
void loop()
{
loop_buttons();
if (!client.connected())
{
reconnect();
}
client.loop();
static unsigned long lastentry = 0;
static unsigned long lastentry2 = 0;
if (millis() - lastentry > 200)
{
pinMode(2, OUTPUT);
digitalWrite(2, !digitalRead(2));
lastentry = millis();
}
delay(50);
if (millis() - lastentry2 > 1000)
{
Serial.println(ESP.getFreeHeap());
lastentry2 = millis();
}
}
Originally posted by @guydvir2 in #6543 (comment)