I am working on a project were I am putting my board into deep sleep mode, and it wakes up with an interrupt from a sensor. When it wakes from deep sleep I would like to send a message to my MQTT broker. The wiring works, the interrupt works, however, the code does not.

When I use the posted code, everything looks fine in the console, I get all my print statements which would make me assume it is working. However, my MQTT broker does not show any messages. But, if I move "sendMQTTMessage()" to the loop function it works fine and the messages come through to my broker.

Any suggestions would be greatly appreciated

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

const char* ssid = "*";
const char* ss_pswd = "*";
const char* mqtt_server = "*";
WiFiClient EspClient;
PubSubClient client(EspClient);

void wifi_setup() {
  Serial.print("Connecting to: ");
  WiFi.begin(ssid, ss_pswd);
  while (WiFi.status() != WL_CONNECTED) {
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    String ClientId = "ESP8266";
    ClientId += String(random(0xffff), HEX);
    if (client.connect(ClientId.c_str())) {
      client.publish("outtopic", "hello world, finally");
    } else {
      Serial.print("failed, rc=");
      Serial.println("Try again...");
void sendMQTTMessage() {
  Serial.println("sending your message");
  if (!client.connected()) {
  client.publish("belmont/sensor/pir/hallway", "on");
void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived: ");
  for (int i = 0; i < length; i++) {
void setup() {
  client.setServer(mqtt_server, 1883);
  Serial.println("going into deep sleep");
  ESP.deepSleep(10 * 1000000);

void loop() {
//  sendMQTTMessage();
//  delay(5000);
  • messages come through to my broker ..... so, what is the actual problem and what is your question? – jsotola Feb 3 at 1:50
  • They only come through my broker, when I place "sendMQTTMessage()" inside of the loop function WITHOUT putting it into a deep sleep. The minute I start using deep sleep I get no messages on broker. – Paul Carlson Feb 3 at 2:21
  • does any of Attempting MQTT connection... get output? – Jaromanda X Feb 3 at 2:48
  • 4
    try a delay after send – Juraj Feb 3 at 7:05

The answer for this actually goes to Juraj. It was the fact that I was missing a delay. In hindsight it makes sense, as even though I am competing tasks in order, the system is shutting down, before the actual message is sent. I added a delay(1000) between the "sendMQTTMessage()" and "ESP.deepsleep()" and it worked.

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