From 061a084f1d18e707858754dc43d7abad40a55156 Mon Sep 17 00:00:00 2001
From: damage <damage@devloop.de>
Date: Sat, 17 May 2025 15:06:48 +0200
Subject: [PATCH] keepalive mqtt message by loops, not by time

faster during runtime, calculation not needed
---
 master/master.ino | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/master/master.ino b/master/master.ino
index 89214e8..a8d969c 100644
--- a/master/master.ino
+++ b/master/master.ino
@@ -19,7 +19,7 @@
 #define MQTT_SIM_LOG_TOPIC "/xplane/meta/log"
 #define MQTT_SIM_VALUE_TOPIC "/xplane/rref/#"
 
-#define MQTT_KEEPALIVE_INTERVAL_MS 15000
+#define MQTT_KEEPALIVE_INTERVAL_LOOPS 60000
 
 struct device {
   byte address;       // I2C address of device
@@ -47,7 +47,7 @@ const char topic[]  = MQTT_SIM_VALUE_TOPIC;
 EthernetClient client;
 char localIP[16];
 MqttClient mqttClient(client);
-unsigned long mqttLastKeepAlive = millis();
+int mqttLastKeepAlive = 0;
 
 void onMqttMessage(int messageSize) {
 //  // we received a message, print out the topic and contents
@@ -174,10 +174,11 @@ void loop() {
     }
   }
 
-  // transmit MQTT keepalive message if MQTT_KEEPALIVE_INTERVAL_MS is reached
-  // or millis() is wrapping to 0
-  if (mqttLastKeepAlive + MQTT_KEEPALIVE_INTERVAL_MS < millis() || mqttLastKeepAlive > millis()) {
+  // transmit MQTT keepalive message every MQTT_KEEPALIVE_INTERVAL_LOOPS times
+  // running the loop
+  mqttLastKeepAlive++;
+  if (mqttLastKeepAlive >= MQTT_KEEPALIVE_INTERVAL_LOOPS) {
     sendMqttMessage(MQTT_SIM_DEVICE_TOPIC, 1, localIP);
-    mqttLastKeepAlive = millis();
+    mqttLastKeepAlive = 0;
   }
 }