Improve memory handling and analog resolution setup

Set analogReadResolution to 12 bits in the client to match sensor divisor. On the server, allocate DynamicJsonDocument on the heap to prevent stack overflow and increase buffer size for client config serialization to 4096 bytes. Added clarifying comments for RPM calculation and memory handling.

Author: dorkmo

TankAlarm-112025-Client-BluesOpta/TankAlarm-112025-Client-BluesOpta.ino

@@ -327,6 +327,9 @@ void setup() {
   Serial.println();
   Serial.println(F("Tank Alarm Client 112025 starting"));
 
+  // Set analog resolution to 12-bit to match the /4095.0f divisor used in readTankSensor
+  analogReadResolution(12);
+
   initializeStorage();
   ensureConfigLoaded();
   printHardwareRequirements(gConfig);
@@ -1268,6 +1271,7 @@ static float readTankSensor(uint8_t idx) {
       // Calculate RPM from pulse count
       // Formula: RPM = (pulses / sample_duration_seconds) * 60 seconds/minute / pulses_per_revolution
       // Simplified: RPM = (pulses * 60000) / (sample_duration_ms * pulses_per_rev)
+      // Note: Max RPM is limited by the polling loop speed (approx 30,000 RPM at 1 pulse/rev), which is sufficient.
       const float MS_PER_MINUTE = 60000.0f;
       uint8_t pulsesPerRev = (cfg.pulsesPerRevolution > 0) ? cfg.pulsesPerRevolution : 1;
       float rpm = ((float)pulseCount * MS_PER_MINUTE) / ((float)RPM_SAMPLE_DURATION_MS * (float)pulsesPerRev);

TankAlarm-112025-Server-BluesOpta/TankAlarm-112025-Server-BluesOpta.ino

@@ -3308,7 +3308,13 @@ static void sendTankJson(EthernetClient &client) {
 }
 
 static void sendClientDataJson(EthernetClient &client) {
-  DynamicJsonDocument doc(CLIENT_JSON_CAPACITY);
+  // Allocate large JSON document on heap instead of stack to prevent overflow
+  DynamicJsonDocument *docPtr = new DynamicJsonDocument(CLIENT_JSON_CAPACITY);
+  if (!docPtr) {
+    respondStatus(client, 500, F("Server Out of Memory"));
+    return;
+  }
+  DynamicJsonDocument &doc = *docPtr;
 
   JsonObject serverObj = doc.createNestedObject("server");
   serverObj["name"] = gConfig.serverName;
@@ -3407,9 +3413,11 @@ static void sendClientDataJson(EthernetClient &client) {
   String json;
   if (serializeJson(doc, json) == 0) {
     respondStatus(client, 500, F("Failed to encode client data"));
+    delete docPtr;
     return;
   }
   respondJson(client, json);
+  delete docPtr;
 }
 
 static void handleConfigPost(EthernetClient &client, const String &body) {
@@ -3605,7 +3613,7 @@ static bool sendRelayCommand(const char *clientUid, uint8_t relayNum, bool state
 }
 
 static ConfigDispatchStatus dispatchClientConfig(const char *clientUid, JsonVariantConst cfgObj) {
-  char buffer[1536];
+  char buffer[4096];
   size_t len = serializeJson(cfgObj, buffer, sizeof(buffer));
   if (len == 0 || len >= sizeof(buffer)) {
     Serial.println(F("Client config payload too large"));