use the stack for buffers

src/main.cpp

@@ -187,9 +187,9 @@ void ICACHE_FLASH_ATTR sendValues() {
   if (sd.cpm > 0)    DEBUG_MSG("Radiation    : %6.2fµSv/h (J305)\n", sd.radioactivity);
                   DEBUG_MSG("Voltage      : %6.2fV     (ESP8266)\n", sd.voltage);
 
-  DynamicJsonBuffer jsonBuffer;
+  StaticJsonBuffer<MQTT_MAX_PACKET_SIZE> jsonBuffer;
   JsonArray& array = jsonBuffer.createArray();
-  DynamicJsonBuffer jsonBuffer2;
+  StaticJsonBuffer<MQTT_MAX_PACKET_SIZE> jsonBuffer2;
   JsonObject& root = jsonBuffer.createObject();
 
   JsonObject& temperatureObject = array.createNestedObject();
@@ -245,7 +245,7 @@ void ICACHE_FLASH_ATTR sendValues() {
   root["heap"] = ESP.getFreeHeap();
 
 
-  char buffer[500];
+  char buffer[MQTT_MAX_PACKET_SIZE];
   array.printTo(buffer, sizeof(buffer));
 
   WiFi.forceSleepWake();