From b26b8615d42db666b07997e9bb06a8abcfff23ec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=BCbbe=20Onken?= <luebbe.opensource@gmail.com>
Date: Sun, 20 Aug 2023 16:46:16 +0200
Subject: [PATCH] Give all sensor nodes an individual random start delay so
 that they are not all read at the same time.

---
 src/AdcNode.cpp     |  5 +++--
 src/BME280Node.cpp  |  6 ++----
 src/DHT22Node.cpp   |  4 ++--
 src/DS18B20Node.cpp |  4 ++--
 src/SensorNode.cpp  | 22 ++++++++++++++++------
 src/SensorNode.hpp  | 11 ++++++-----
 6 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/src/AdcNode.cpp b/src/AdcNode.cpp
index df5e1fe..24099f9 100644
--- a/src/AdcNode.cpp
+++ b/src/AdcNode.cpp
@@ -126,7 +126,8 @@ void AdcNode::beforeHomieSetup()
 
 void AdcNode::setup()
 {
-  printCaption();
-  Homie.getLogger() << cIndent << F("Send interval: ") << _sendInterval / 1000 << " s" << endl;
+  SensorNode::setup();
+
+  Homie.getLogger() << cIndent << F("Reading interval: ") << readInterval() / 1000UL << F("s") << endl;
   _sensorFound = true;
 }
diff --git a/src/BME280Node.cpp b/src/BME280Node.cpp
index 0529852..94658c1 100644
--- a/src/BME280Node.cpp
+++ b/src/BME280Node.cpp
@@ -116,16 +116,14 @@ void BME280Node::onReadyToOperate()
 
 void BME280Node::setup()
 {
-  printCaption();
+  SensorNode::setup();
 
   if (bme.begin(_i2cAddress))
   {
     _sensorFound = true;
-    Homie.getLogger() << cIndent << F("found. Reading interval: ") << readInterval() / 1000UL << F(" s") << endl;
-    // Parameters taken from the weather station monitoring example (advancedsettings.ino) in
-    // the Adafruit BME280 library
     bme.setSampling(Adafruit_BME280::MODE_FORCED, _tempSampling, _pressSampling, _humSampling, _filter);
     bme.setTemperatureCompensation(_temperatureOffset->get());
+    Homie.getLogger() << cIndent << F("found. Reading interval: ") << readInterval() / 1000UL << F("s") << endl;
   }
   else
   {
diff --git a/src/DHT22Node.cpp b/src/DHT22Node.cpp
index 6e184af..c69d0a5 100644
--- a/src/DHT22Node.cpp
+++ b/src/DHT22Node.cpp
@@ -85,12 +85,12 @@ void DHT22Node::takeMeasurement()
 
 void DHT22Node::setup()
 {
-  printCaption();
-  Homie.getLogger() << cIndent << F("Reading interval: ") << readInterval() / 1000UL << F(" s") << endl;
+  SensorNode::setup();
 
   if (dht)
   {
     dht->begin();
     _sensorFound = true;
+    Homie.getLogger() << cIndent << F("Reading interval: ") << readInterval() / 1000UL << F("s") << endl;
   }
 }
diff --git a/src/DS18B20Node.cpp b/src/DS18B20Node.cpp
index 1d106c1..c166cf7 100644
--- a/src/DS18B20Node.cpp
+++ b/src/DS18B20Node.cpp
@@ -80,13 +80,13 @@ void DS18B20Node::onReadyToOperate()
 
 void DS18B20Node::setup()
 {
-  printCaption();
+  SensorNode::setup();
 
   if (dallasTemp)
   {
     dallasTemp->begin();
     _sensorFound = (dallasTemp->getDS18Count() > 0);
     Homie.getLogger() << cIndent << F("Found ") << dallasTemp->getDS18Count() << " sensors." << endl
-                      << cIndent << F("Reading interval: ") << readInterval() / 1000UL << F(" s") << endl;
+                      << cIndent << F("Reading interval: ") << readInterval() / 1000UL << F("s") << endl;
   }
 }
diff --git a/src/SensorNode.cpp b/src/SensorNode.cpp
index c5c43da..77edadc 100644
--- a/src/SensorNode.cpp
+++ b/src/SensorNode.cpp
@@ -15,8 +15,8 @@ SensorNode::SensorNode(const char *id, const char *name, const char *type,
     : BaseNode(id, name, type),
       _readInterval(readInterval),
       _sendInterval(sendInterval),
-      _lastReadTime(0),
-      _lastSendTime(0)
+      _nextReadTime(0),
+      _nextSendTime(0)
 {
 }
 
@@ -64,22 +64,32 @@ bool SensorNode::sensorFound()
   return _sensorFound;
 }
 
+void SensorNode::setup()
+{
+  printCaption();
+  // Give all sensors a random start delay from one to five seconds, 
+  // so they are not all read at the same time.
+  long randomDelay = random(1000, 5000);
+  _nextReadTime = randomDelay;
+  _nextSendTime = randomDelay;
+}
+
 void SensorNode::loop()
 {
   if (sensorFound())
   {
     unsigned long now = millis();
 
-    if (now - _lastReadTime >= readInterval() || _lastReadTime == 0)
+    if (now >= _nextReadTime)
     {
       takeMeasurement();
-      _lastReadTime = now;
+      _nextReadTime = now + readInterval();
     }
 
-    if (now - _lastSendTime >= _sendInterval || _lastSendTime == 0)
+    if (now >= _nextSendTime)
     {
       send();
-      _lastSendTime = now;
+      _nextSendTime = now + sendInterval();
       if (_onDataSent != NULL)
       {
         _onDataSent();
diff --git a/src/SensorNode.hpp b/src/SensorNode.hpp
index 80262f7..18f27c7 100644
--- a/src/SensorNode.hpp
+++ b/src/SensorNode.hpp
@@ -22,8 +22,8 @@ class SensorNode : public BaseNode
 
   unsigned long _readInterval;
   unsigned long _sendInterval;
-  unsigned long _lastReadTime;
-  unsigned long _lastSendTime;
+  unsigned long _nextReadTime;
+  unsigned long _nextSendTime;
   bool _sensorFound = false;
 
   const float cMinHumid = 0.0;
@@ -34,20 +34,21 @@ class SensorNode : public BaseNode
   float computeAbsoluteHumidity(float tempCelsius, float percentHumidity);
   float computeDewpoint(float tempCelsius, float percentHumidity);
 
-  virtual unsigned long readInterval();
-  virtual unsigned long sendInterval();
-
   virtual void send() = 0;
   virtual bool sensorFound();
   virtual void takeMeasurement() = 0;
 
   virtual void loop() override;
+  virtual void setup() override;
 
 public:
   explicit SensorNode(const char *id, const char *name, const char *type,
                       const int readInterval = READ_INTERVAL,
                       const int sendInterval = SEND_INTERVAL);
 
+  virtual unsigned long readInterval();
+  virtual unsigned long sendInterval();
+
   void SetOnDataSent(TOnDataSent OnDataSent)
   {
     _onDataSent = OnDataSent;