diff --git a/main/SENSORDATA.md b/main/SENSORDATA.md
new file mode 100644
index 0000000..8bb43bf
--- /dev/null
+++ b/main/SENSORDATA.md
@@ -0,0 +1,80 @@
+# MQTT message structure
+## MSG Header
+Every message. Total len 18 bytes.
+```mermaid
+block-beta
+    T["<b>TIME</b><br>4 bytes<br>seconds"]:2
+	Tm["<b>TIME</b><br>4 bytes<br>useconds"]:2
+    MAC["WIFI MAC<br>6 bytes"]:3
+    GRP["Group id<br>4 bytes"]:2
+```
+# Block messages
+
+## Radar message
+Arrives every 10 seconds. Total len 49 + 18 = 67 bytes
+```mermaid
+block-beta
+    MSG_HEADER
+    B["0x10"]
+    C["14 uint16<br>motion energy"]
+	D["10 uint16<br>stationary energy"]
+```
+<br>
+
+## Sensors message
+Arrives every 10 seconds, when gas sensor data has been collected. Total len: 18 + 16 + 5 * number_data_pairs
+```mermaid
+block-beta
+    MSG_HEADER:1
+    B["0x11"]:1
+    C["Pressure<br>float"]:1
+	D["Temperature<br>float"]:1
+	E["light<br>2 bytes"]:1
+	F["humidity<br>float"]:1
+	G["Number of data pairs<br>byte"]:1
+	block:aa:3
+	H["index 1<br>byte"]
+	I["gas resistance 1<br>float"]
+	J["..."]
+	end
+```
+
+<br>
+
+# Notification messages
+
+## Pressure
+Total len: 18 + 5 = 23 bytes
+```mermaid
+block-beta
+    MSG_HEADER
+    B["0x01"]
+    C["value<br>float"]
+```
+
+## Temperature
+Total len: 18 + 5 = 23 bytes
+```mermaid
+block-beta
+    MSG_HEADER
+    B["0x02"]
+    C["value<br>float"]
+```
+
+## Humidity
+Total len: 18 + 5 = 23 bytes
+```mermaid
+block-beta
+    MSG_HEADER
+    B["0x03"]
+    C["value<br>float"]
+```
+
+## Light
+Total len: 18 + 3 = 21 bytes
+```mermaid
+block-beta
+    MSG_HEADER
+    B["0x04"]
+    C["value<br>2 bytes"]
+```
diff --git a/main/SensorData.h b/main/SensorData.h
index 64a7b56..4782632 100644
--- a/main/SensorData.h
+++ b/main/SensorData.h
@@ -1,12 +1,12 @@
 /// © MiroZ 2024
 #ifndef __SENSOR_DATA_H__
 #define __SENSOR_DATA_H__
-
 #include <stdint.h>
 
+
 #pragma pack(push, 1)
 
-struct MESSAGE_HEADER
+struct MESSAGE_HEADER	// 19 bytes
 {
 	uint8_t type;
 	uint32_t sec;
@@ -22,12 +22,38 @@ struct MESSAGE_TYPE_VAL_REASON
 	uint8_t reason;
 };
 
-struct RADAR
+struct RADAR	// 49
 {
 	uint8_t type;
 	uint16_t vals[24];
 };
 
+struct GAS_HEADER	// 2 bytes
+{
+	uint8_t type;
+	uint8_t num_measurements;
+};
+
+struct GAS_DATA	//5 bytes
+{
+	uint8_t index;
+	float gas_resistance;
+};
+
+struct OTHERS
+{
+	float pressure;
+	float temp;
+	uint16_t light;
+};
+
+struct GAS	// 6 + num_gas_data * 5
+{
+	struct GAS_HEADER header;
+	float humidity;
+	struct GAS_DATA data[0];
+};
+
 #pragma pack(pop)
 
 #define HEADER_MESSAGE(name_) \
@@ -98,14 +124,25 @@ struct RADAR
 #define RADAR_MESSAGE_P(addr_) \
 	(addr_)->type = MESSAGE_TYPE_RADAR;
 
+#define GAS_MESSAGE(name_, num_vals_) \
+	struct GAS name_; \
+	name_.header.type = MESSAGE_TYPE_GAS; \
+	name_.header.num_measurements = num_vals_;
+
+#define GAS_MESSAGE_P(addr_, num_vals_) \
+	(addr_)->header.type = MESSAGE_TYPE_GAS; \
+	(addr_)->header.num_measurements = num_vals_;
+
 #define MESSAGE_TYPE_HEADER			0xa5
 #define MESSAGE_TYPE_PRESSURE		0x04
 #define MESSAGE_TYPE_RADAR			0x37
 #define MESSAGE_TYPE_LIGHT			0x06
 #define MESSAGE_TYPE_TEMP			0x07
 #define MESSAGE_TYPE_HUMIDITY		0x08
-#define MESSAGE_TYPE_GAS_IX			0x09
-#define MESSAGE_TYPE_GAS_VAL		0x0a
+#define MESSAGE_TYPE_GAS_IX			0x09	// deprecated
+#define MESSAGE_TYPE_GAS_VAL		0x0a	// deprecated
+#define MESSAGE_TYPE_GAS			0x0b
+#define MESSAGE_TYPE_SENSOR_BLOCK	0x0c
 
 void createHeader(struct MESSAGE_HEADER * header);
 
diff --git a/main/sensors/Bme68x.cpp b/main/sensors/Bme68x.cpp
index 52a7bd4..aa16f1c 100644
--- a/main/sensors/Bme68x.cpp
+++ b/main/sensors/Bme68x.cpp
@@ -35,12 +35,16 @@ bool Bme68x::init()
 	return m_operational;
 }
 
-
-void Bme68x::read(struct BME_DATA * data)
+/// @brief 
+/// @param data 
+/// @return returns true when index 9 is read
+bool Bme68x::read(struct BME_DATA * data)
 {
 	MyLibs::bme68xData bdata;
 	uint8_t left;
 
+	bool ret_val = false;
+
 	if(m_sensor->fetchData() > 0)
 	{
 		do
@@ -50,13 +54,19 @@ void Bme68x::read(struct BME_DATA * data)
 			if (bdata.status == NEW_GAS_MEAS)
 			{
 				int ix = _min(bdata.gas_index, 9);
+	
+				ESP_LOGW(TAG, "index: %d", ix);
+
+				data->measurement_bitmask |= (1 << ix);
 
 				if(ix == 0)
 					data->humidity = bdata.humidity;
+				else if(ix == 9)
+					ret_val = true;
 
 				data->measurement[ix].resistance = bdata.gas_resistance;
-				data->measurement[ix].temp = bdata.temperature;
 			}
 		} while(left > 0);
 	}
+	return ret_val;
 }
\ No newline at end of file
diff --git a/main/sensors/Bme68x.h b/main/sensors/Bme68x.h
index 5dbc06f..3db7ea1 100644
--- a/main/sensors/Bme68x.h
+++ b/main/sensors/Bme68x.h
@@ -9,13 +9,13 @@
 
 struct GAS_MEASUREMENT
 {
-	float temp;
 	float resistance;
 };
 
 struct BME_DATA
 {
 	float humidity;
+	uint16_t measurement_bitmask;
 	struct GAS_MEASUREMENT measurement[10];
 };
 
@@ -30,7 +30,7 @@ public:
 	Bme68x(TwoWire & bus);
 	bool init();
 
-	void read(struct BME_DATA * data);
+	bool read(struct BME_DATA * data);
 };
 
 #endif
\ No newline at end of file
diff --git a/main/sensors/SensorService.cpp b/main/sensors/SensorService.cpp
index bca5864..77ad793 100644
--- a/main/sensors/SensorService.cpp
+++ b/main/sensors/SensorService.cpp
@@ -51,51 +51,105 @@ void SensorService::start()
 	pinMode(LIGHT_SENSOR_PIN, INPUT);
 }
 
+void SensorService::postBme68xData(float pressure, float temp)
+{
+	struct msg
+	{
+		struct MESSAGE_HEADER header;
+		struct OTHERS others;
+		struct GAS gas;
+	};
+
+	uint8_t msg_buffer[100];
+
+	struct msg *data_to_send = (struct msg *)msg_buffer;
+
+	HEADER_MESSAGE_P(&data_to_send->header);
+	GAS_MESSAGE_P(&data_to_send->gas, 0);
+	
+	data_to_send->others.light = m_light_value;
+	data_to_send->others.pressure = pressure;
+	data_to_send->others.temp = temp;
+
+	int num_total = 0;
+	
+	struct GAS_DATA * p = data_to_send->gas.data;
+	for(int n = 0; n < 10; n++)
+	{
+		if(m_bme_data.measurement_bitmask & (1 << n))
+		{
+			p[num_total].gas_resistance = m_bme_data.measurement[n].resistance;
+			p[num_total++].index = n;
+		}
+	}
+
+	data_to_send->gas.header.num_measurements = num_total;
+	data_to_send->gas.humidity = m_bme_data.humidity;
+
+	m_app_if.getBuffer()->putBlock((uint8_t*)&data_to_send, sizeof(*data_to_send) + num_total * sizeof(struct GAS_DATA));
+
+	// clear the blackboard
+	memset(&m_bme_data, 0, sizeof(m_bme_data));
+}
+
+/// @brief Actual light value is minimum in 2s window
+/// @param light_value 
+void SensorService::processLight(int light_value)
+{
+	static uint16_t min_light_val = 0xffff;
+	static int last_light_val = -1;
+	static uint64_t last_time = esp_timer_get_time();
+	uint64_t now;
+
+	// handle light sensor
+	if(light_value < min_light_val)
+		min_light_val = light_value;
+
+	now = esp_timer_get_time();
+
+	if(now - last_time >= 2000000)	// >= 2s
+	{
+		ESP_LOGI(TAG, "light: %d", min_light_val);
+		if(last_light_val >= 0)
+		{
+			if(abs(min_light_val - last_light_val) > 4096*5/100)
+			{
+				ESP_LOGI(TAG, "light tripped");
+				struct msg
+				{
+					struct MESSAGE_HEADER header;
+					struct MESSAGE_TYPE_VAL_REASON light;
+				};
+
+				struct msg m;
+				HEADER_MESSAGE_P(&m.header);
+				LIGHT_MESSAGE_P(&m.light, min_light_val, 1);
+				m_app_if.getBuffer()->putBlock((uint8_t*)&m, sizeof(m));
+			}
+		}
+		last_light_val = min_light_val;
+		m_light_value = min_light_val;
+		min_light_val = 0xffff;
+		last_time = now;
+	}
+}
+
 // handles pressure and voc sensor
 void SensorService::run_i2c_1()
 {
-	uint16_t light_val = 0xffff;
-	int last_light_val = -1;
-	uint64_t last_time = esp_timer_get_time(), now;
-
 	while(true)
 	{
 		m_bmp280->read(m_bmp_data.temp, m_bmp_data.pressure);
-		m_bme68x->read(&m_bme_data);
+		bool bme_cycle_finished = m_bme68x->read(&m_bme_data);
 		uint16_t read_light_val = analogRead(LIGHT_SENSOR_PIN);
 
-		// handle light sensor
-		if(read_light_val < light_val)
-			light_val = read_light_val;
-
-		now = esp_timer_get_time();
-
-		if(now - last_time >= 2000000)	// >= 2s
+		if(bme_cycle_finished)
 		{
-			ESP_LOGI(TAG, "light: %d", light_val);
-			if(last_light_val >= 0)
-			{
-				if(abs(light_val - last_light_val) > 4096*5/100)
-				{
-					ESP_LOGI(TAG, "light tripped");
-					struct msg
-					{
-						struct MESSAGE_HEADER header;
-						struct MESSAGE_TYPE_VAL_REASON light;
-					};
-
-					struct msg m;
-					HEADER_MESSAGE_P(&m.header);
-					LIGHT_MESSAGE_P(&m.light, light_val, 1);
-					m_app_if.getBuffer()->putBlock((uint8_t*)&m, sizeof(m));
-				}
-			}
-			last_light_val = light_val;
-			light_val = 0xffff;
-			last_time = now;
+			postBme68xData(m_bmp_data.pressure, m_bmp_data.temp);
 		}
 
-		
+		processLight(read_light_val);
+
 		delay(10);
 	}
 }
diff --git a/main/sensors/SensorService.h b/main/sensors/SensorService.h
index f7cad4e..3e7cc2a 100644
--- a/main/sensors/SensorService.h
+++ b/main/sensors/SensorService.h
@@ -28,6 +28,11 @@ protected:
 
 	AppIF & m_app_if;
 
+	void postBme68xData(float pressure, float temp);
+	void processLight(int light_value);
+	void processHumidity(float humidity);
+	uint16_t m_light_value = 0;
+
 public:
 	SensorService(AppIF & app_if);
 	void start();