Add a new packet format with the calculation of the CRC

weather-sensor/firmware/crc.c

@@ -45,7 +45,7 @@ uint16_t Calculate_Crc(const uint8_t *buffer, uint8_t size)
 
 	for (uint8_t i = 0; i < size; i++)
 	{
-		crc = (crc >> 8) ^ crcTable[ (crc ^ (uint16_t) *tempPointer) & 0x00FF ];
+		crc = (crc >> 8) ^ pgm_read_word(&crcTable[ (crc ^ (uint16_t) *tempPointer) & 0x00FF ]);
 		tempPointer++;
 	}
 

weather-sensor/firmware/crc.h

@@ -1 +1,5 @@
+#ifndef CRC_H
+#define CRC_H
+
 uint16_t Calculate_Crc(const uint8_t *buffer, uint8_t size);
+#endif

weather-sensor/firmware/main.c

@@ -15,6 +15,7 @@
 #include "bme280_interface.h"
 #include "bme280_defs.h"
 #include "pin_programming.h"
+#include "crc.h"
 
 
 
@@ -32,6 +33,10 @@ volatile uint8_t interruptCounter;
 volatile uint8_t executionFlag;
 
 
+
+static PACKET reportPacket;
+
+
 void Enter_Power_Save_Mode(void);
 void Exit_Power_Save_Mode(void);
 
@@ -64,11 +69,7 @@ ISR(PCINT2_vect)
 int main (void)
 {
 	struct bme280_data sensorData;
-	struct DATA_PACKET dataPacket;
-//	uint8_t testRegisterContent = 0x0A;
-//	uint8_t registerContent[5];
-//	char registerContentString[30];
-//	uint8_t lengthRead;
+	uint16_t crc;
 
 	/* Enable the debug LED */
 	LED_DDR |= (1 << LED_PIN);
@@ -112,11 +113,30 @@ int main (void)
 			/* Get measurement and send it */
 			BME280_Get_Measurement(&sensorData);
 
-			dataPacket.senderId = ownId;
-			dataPacket.temperature = sensorData.temperature;
-			dataPacket.pressure = sensorData.pressure;
-			dataPacket.humidity = sensorData.humidity;
-			NRF24L01_Send_Message((uint8_t*)&dataPacket, sizeof(dataPacket));
+
+			memset((uint8_t*)&reportPacket, 0, sizeof(reportPacket)); //Reinitialize the buffer with zeros
+
+			reportPacket.senderId = ownId;
+			//reportPacket.salt; /* TODO */
+			reportPacket.payload.values.packetIdentifier.elementCount = 3;
+			reportPacket.payload.values.packetIdentifier.packetType = 0; /* TODO: report type ? */
+
+			/* Fill in the payload */
+			reportPacket.payload.values.valueTypeTemperature = VALUE_TYPE_TEMPERATURE;
+			reportPacket.payload.values.temperature = sensorData.temperature;
+			reportPacket.payload.values.valueTypePressure = VALUE_TYPE_PRESSURE;
+			reportPacket.payload.values.pressure = sensorData.pressure;
+			reportPacket.payload.values.valueTypeHumidity = VALUE_TYPE_HUMIDITY;
+			reportPacket.payload.values.humidity = sensorData.humidity;
+
+			/* Calculate the CRC */
+			crc = Calculate_Crc(reportPacket.payload.buffer, PACKET_BUFFER_LENGTH);
+			reportPacket.crc = crc;
+
+			/* Encrypt the packet */
+			/* TODO */
+
+			NRF24L01_Send_Message((uint8_t*)&reportPacket, sizeof(reportPacket));
 
 			_delay_ms(100); /* TODO: only for debugging, remove this later! */
 			LED_PORT &= ~(1 << LED_PIN);

weather-sensor/firmware/nrf24l01.h

@@ -1,7 +1,7 @@
 #ifndef NRF24L01_H
 #define NRF24L01_H
 
-
+#define PACKET_BUFFER_LENGTH 22
 
 /* AVR I/O pin definionts */
 #define NRF_CE_DDR   DDRD
@@ -17,6 +17,7 @@
 #define NRF_IRQ_PIN     PD5
 #define NRF_IRQ_PORTIN  PIND
 
+
 void Initialize_NRF24L01(void);
 void Set_NRF24L01_Pins(void);
 void Configure_Transmission(uint8_t moduleId);
@@ -30,12 +31,40 @@ void Write_Message_To_TX_FIFO(uint8_t length, uint8_t * buffer);
 void Set_TX_Address(uint8_t * txAddress, uint8_t length);
 void Set_RX_P0_Address(uint8_t * rxAddress, uint8_t length);
 
-typedef struct __attribute__ ((packed)) DATA_PACKET
+typedef enum
+{
+	VALUE_TYPE_TIME = 0,
+	VALUE_TYPE_TEMPERATURE = 1,
+	VALUE_TYPE_PRESSURE = 2,
+	VALUE_TYPE_HUMIDITY = 3,
+} VALUE_TYPES;
+
+typedef struct __attribute__((packed)) BITFIELD_PACKET_COUNT_ELEMENT
+{
+	uint8_t elementCount : 3;
+	uint8_t packetType : 5;
+} BITFIELD_PACKET_COUNT_ELEMENT;
+
+typedef struct __attribute__((packed)) PACKET
 {
 	uint8_t senderId;
-	uint32_t pressure;
-	int32_t temperature;
-	uint32_t humidity;
-} DATA_PACKET;
+	uint8_t salt[7];
+	union {
+		struct {
+			BITFIELD_PACKET_COUNT_ELEMENT packetIdentifier;
+			uint8_t valueTypeTemperature;
+			int16_t temperature;
+			uint8_t valueTypePressure;
+			uint32_t pressure;
+			uint8_t valueTypeHumidity;
+			uint16_t humidity;
+			uint8_t unused[10];
+		} values;
+		uint8_t buffer[PACKET_BUFFER_LENGTH];
+	}payload;
+	//uint8_t buffer[PACKET_BUFFER_LENGTH];
+	uint16_t crc;
+} PACKET;
+
 
 #endif