Usage Example for Arduino-Connect Azure IoT and Send Data

Hardware Preparation

• DFRduino UNO R3 + IGravity:IO Expansion Shield (or similar) x 1
• Gravity: Analog LM35 Temperature Sensor For Arduino x1
• OBLOQ module x 1
• some connecting wires

Software Preparation

• Arduino IDE, Click to Download Arduino IDE from Arduino®

Create Azure IoT Device

• Register a device in the IoT hub for your device
• Make a note of the primary key of the connection string.
• Device Explorer tool and how to use it

Wiring Diagram

• TX-Pin10,
• RX-Pin11
• A0-LM35
• GND-GND
• VCC-VCC

Sample Code

• Functions realized: Arduino reads temperature data from LM35, and sends the data to Azure IoT device via OBLOQ module.

#include <Arduino.h>
#include <SoftwareSerial.h>

//Initialize OBLOQ
Obloq olq(&softSerial, "SeiferNet", "7106230000", "iot_s1.dfrobot.com","1883", "HJ-LCn_HS7", "HJzUCnurSm");

//wifi SSID and password
#define WIFISSID "DFRobot-guest"
#define WIFIPWD  "dfrobot@2017"

//Azure IOT device connection string, this string need modification when connect to different devices
const String connectionString = "HostName=dfrobot.azure-devices.cn;DeviceId=temperature;SharedAccessKey=CR5gUclNaT7skX9WP+e6oIB/BnkZnTIEReKBX870SNY=";
const String separator = "|";
bool pingOn = true;
bool createIoTClientSuccess = false;
static unsigned long previoustGetTempTime = 0;
static unsigned long pingInterval = 2000;
static unsigned long sendMessageInterval = 10000;
unsigned long previousPingTime = 0;
String receiveStringIndex[10] = {};

//Disconnected wifi detection variable
bool wifiConnect = false;
bool wifiAbnormalDisconnect = false;

SoftwareSerial softSerial(10,11);

enum state{
    WAIT,
    PINGOK,
    WIFIOK,
    AZURECONNECT
}obloqState;

/********************************************************************************************
Function    : sendMessage
Description : send message via serial port
Params      : message : message content, it is a string
Return      : None
********************************************************************************************/
void sendMessage(String message)
{
    softSerial.print(message+"\r");
}

/********************************************************************************************
Function    : ping
Description : Check if the serial communication is normal. When Obloq serial port receives the pingcommand, it will return: |1|1|\r
Return      : None
********************************************************************************************/
void ping()
{
    String pingMessage = F("|1|1|");
    sendMessage(pingMessage);
}

/********************************************************************************************
Function    : connectWifi
Description : Connect wifi, once successfully connected Obloq returns: |2|3|ip|\r
Params      : ssid : wifi SSID
Params      : pwd :  wifi password
Return      : None
********************************************************************************************/
void connectWifi(String ssid,String pwd)
{
    String wifiMessage = "|2|1|" + ssid + "," + pwd + separator;
    sendMessage(wifiMessage);
}

/********************************************************************************************
Function    : createIoTClient
Description : Create device client handle, once successfully created Obloq returns: |4|2|1|1|\r
Params      : connecttionString  device connection string
Return      : None
********************************************************************************************/
void createIoTClient(String connecttionString)
{
    String azureConnectMessage = "|4|2|1|" + connecttionString + separator;
    sendMessage(azureConnectMessage);
}

/********************************************************************************************
Function    : subscribeDevice
Description : Subscribe to device. Obloq returns message content after the device receives message.
Params      : None
Return      : None
********************************************************************************************/
void subscribeDevice()
{
    String subscribeDeviceMessage = "|4|2|2|";
    sendMessage(subscribeDeviceMessage);
}

/********************************************************************************************
Function    : unsubscribeDevice
Description : Unsubscribe to device. Once successfully unsubscribed, Obloq returns: |4|2|6|1|\r
Params      : None
Return      : None
********************************************************************************************/
void unsubscribeDevice()
{
    String unsubscribeDeviceMessage = "|4|2|6|";
    sendMessage(unsubscribeDeviceMessage);
}


/********************************************************************************************
Function    : publish
Description : Publish message. Before this command you must create device client handle first.
Params      : message: message content to publish, once successfully sent, OBloq returns :  |4|2|3|1|\r
Return      : None
********************************************************************************************/
void publish(String message)
{
    String publishMessage = "|4|2|3|" + message + separator;
    sendMessage(publishMessage);
}

/********************************************************************************************
Function    : disconnect
Description : destroy device client handle: |4|2|4|1|\r
Params      : None
Return      : None
********************************************************************************************/
void distoryIotClient()
{
    String distoryIotClientMessage = "|4|2|4|";
    sendMessage(distoryIotClientMessage);
}

/********************************************************************************************
Function    : recreateIoTClient
Description : Recreate device client handle, once created successfully, Obloq returns : |4|2|1|1|\r
Params      : None
Return      : None
********************************************************************************************/
void recreateIoTClient()
{
    String recreateIoTClientMessage = "|4|2|5|";
    sendMessage(recreateIoTClientMessage);
}

/********************************************************************************************
Function    : splitString
Description : split a string
Params      : data:  save the cutted char array
Params      : str: the string that will be cutted
Params      : delimiters: the delimiter that cut string
Return      : None
********************************************************************************************/
int splitString(String data[],String str,const char* delimiters)
{
  char *s = (char *)(str.c_str());
  int count = 0;
  data[count] = strtok(s, delimiters);
  while(data[count]){
    data[++count] = strtok(NULL, delimiters);
  }
  return count;
}

/********************************************************************************************
Function    : handleUart
Description : handle data received by serial port
Params      : None
Return      : None
********************************************************************************************/
void handleUart()
{
    while(softSerial.available() > 0)
    {
        String receivedata = softSerial.readStringUntil('\r');
        const char* obloqMessage = receivedata.c_str();
        if(strcmp(obloqMessage, "|1|1|") == 0)
        {
            Serial.println("Pong");
            pingOn = false;
            obloqState = PINGOK;
        }
        if(strcmp(obloqMessage, "|2|1|") == 0)
        {
            if(wifiConnect)
            {
                wifiConnect = false;
                wifiAbnormalDisconnect = true;
            }
        }
        else if(strstr(obloqMessage, "|2|3|") != 0 && strlen(obloqMessage) != 9)
        {
            Serial.println("Wifi ready");
            wifiConnect = true;
            if(wifiAbnormalDisconnect)
            {
                wifiAbnormalDisconnect = false;
                createIoTClientSuccess = true;
                return;
            }
            obloqState = WIFIOK;
        }
        else if(strcmp(obloqMessage, "|4|2|1|1|") == 0)
        {
            Serial.println("Azure ready");
            createIoTClientSuccess = true;
            obloqState = AZURECONNECT;
        }
    }
}

/********************************************************************************************
Function    : sendPing
Description : Check if serial port is communicating normally
Params      : None
Return      : None
********************************************************************************************/
void sendPing()
{
    if(pingOn && millis() - previousPingTime > pingInterval)
    {
        previousPingTime = millis();
        ping();
    }
}

/********************************************************************************************
Function    : execute
Description : send different command according to different status.
Params      : None
Return      : None
********************************************************************************************/
void execute()
{
    switch(obloqState)
    {
        case PINGOK: connectWifi(WIFISSID,WIFIPWD); obloqState = WAIT; break;
        case WIFIOK: createIoTClient(connectionString);obloqState = WAIT; break;
        case AZURECONNECT : obloqState = WAIT; break;
        default: break;
    }
}

/********************************************************************************************
Function    : getTemp
Description : Get temperature measured by LM35
Params      : None
Return      : None
********************************************************************************************/
float getTemp()
{
    uint16_t val;
    float dat;
    val=analogRead(A0);//Connect LM35 on Analog 0
    dat = (float) val * (5/10.24);
    return dat;
}

/********************************************************************************************
Function    : checkWifiState
Description : Callback function of receiving message
Params      : message: message content string that received
Return      : None
********************************************************************************************/
void checkWifiState()
{
    static unsigned long previousTime = 0;
    if(wifiAbnormalDisconnect && millis() - previousTime > 60000)  // reconnect once per minute after wifi abnormally disconnect
    {
        previousTime = millis();
        createIoTClientSuccess = false;
        connectWifi(WIFISSID,WIFIPWD);
    }
}

void setup()
{
    Serial.begin(9600);
    softSerial.begin(9600);
}

void loop()
{
    sendPing();
    execute();
    handleUart();
    checkWifiState();
    //Sending data every 5 seconds
    if(createIoTClientSuccess && millis() - previoustGetTempTime > 5000)
    {
        previoustGetTempTime = millis();

        //Get data from temperature sensor
        float temperature = getTemp();
        publish((String)temperature);
        Serial.println(temperature);
    }
}

Result Demonstration

After successfully uploading the program to Arduino, reset both OBLOQ module and Arduino. When not connected to the wifi, OBLOQ shows red light, but once connected, OBLOQ will show a green light.

Use the Tool Device Explorer under the "Data" menu, then select the device that you are going to send message to. Then simply monitor it. You will see the uploaded message in the EventHub Data window.

Related Document

Sample code