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Ivan Golubic
Ivan Golubic

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ESP32 Cloud data storage

#esp32 #iot #cloud

In this tutorial we will write a simple code that will read temperature from BME280 sensor, and store this temperature to IoTaaP Storage service.

platformio.ini

As usual we will use PlatformIO for this embedded project, and our platformio.ini should look like this:

[env:release] platform = espressif32 board = esp32dev framework = arduino monitor_speed = 115200 lib_deps = iotaap/IoTaaP OS@^5.2.2 adafruit/Adafruit BME280 Library@^2.2.2 board_build.partitions = partitions/default_fat.csv
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Headers and declaration 

#include <IoTaaP_OS.h> #include <Arduino.h> #include <ArduinoJson.h> #include "Adafruit_BME280.h"  #define TOKEN "<iotaap-link-secret>" // IoTaaP Link Secret  Adafruit_BME280 bme; // I2C IoTaaP_OS iotaapOs("3.2.8"); // Defining Firmware version
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We have to include our headers as usual, since Adafruit_BME280.h requires some functions from Arduino.h, we have to include it also. Additionally we have to declare our bme sensor and create iotaapOs object.

Also we have to define TOKEN, so please do not forget to replace <iotaap-link-secret> with your IoTaaP Link Secret.

setup() function 

void setup() { // BME280 related stuff unsigned status; status = bme.begin(0x76); if (!status) { Serial.println("Could not find a valid BME280 sensor, check wiring, address, sensor ID!"); while (1) delay(10); } iotaapOs.start(); // Start IoTaaP OS iotaapOs.startWifi(); // Connect to WiFi iotaapOs.startMqtt(callback); // Connect to MQTT broker }
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In the first part of the function, we are checking if BME280 is available and working, this is a good practice in this example, to eliminate further issues if sensor is not working properly.

Next, we have to call iotaapOs.start() function to start our IoTaaP OS services, this is followed by iotaapOs.startWifi() to connect to start WiFi service and iotaapOs.startMqtt() to connect to the IoTaaP network, and define MQTT callback function.

callback() function 

void callback(char *topic, byte *message, unsigned int length) { Serial.println("-------#-----#-----#----------"); Serial.println("Received data on the topic:"); Serial.println(topic); // Print topic Serial.println("Data:"); for (int i = 0; i < length; i++) // Print message { Serial.print((char)message[i]); } Serial.println(); Serial.println("------#------#------#---------"); }
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This is basic MQTT callback function that will print received data and topic to our Serial Terminal, it is used to check the status of the service.

loop() function 

void loop() { // Fetch measurements from BME280 sensor float temperatureC = bme.readTemperature(); // Store temperature reading to IoTaaP Storage service, and subscribe to callback topic iotaapOs.storageServiceStore(TOKEN, "temperature", temperatureC, "/pgiIzx7n/storage/response"); delay(5000); }
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This function is repeated constantly, and it will read the temperature from our BME280 sensor and store it in temperatureC variable. Next, we will use iotaapOs.storageServiceStore() function to store our reading to the IoTaaP Storage.

Do not forget to update your token and update your callbackTopic. Also your must have permission to listen on your callback topic.

Reading from IoTaaP Storage

We will use Postman to read from IoTaaP Storage. This step is described in detail here.

After populating some data from our sensor, we will get the following response:

{ "data": [ { "time": "2023-06-27T18:14:20.364Z", "value": 26.32 }, { "time": "2023-06-27T18:14:25.364Z", "value": 27.32 }, { "time": "2023-06-27T18:14:30.364Z", "value": 28.14 } ] }
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Complete code

Below you can find the complete code for this example.

#include <IoTaaP_OS.h> #include <Arduino.h> #include <ArduinoJson.h> #include "Adafruit_BME280.h"  #define TOKEN "<iotaap-link-secret>" // IoTaaP Link Secret  Adafruit_BME280 bme; // I2C IoTaaP_OS iotaapOs("3.2.8"); // Defining Firmware version // IoTaaP Network (MQTT) callback function void callback(char *topic, byte *message, unsigned int length) { Serial.println("-------#-----#-----#----------"); Serial.println("Received data on the topic:"); Serial.println(topic); // Print topic Serial.println("Data:"); for (int i = 0; i < length; i++) // Print message { Serial.print((char)message[i]); } Serial.println(); Serial.println("------#------#------#---------"); } void setup() { // BME280 related stuff unsigned status; status = bme.begin(0x76); if (!status) { Serial.println("Could not find a valid BME280 sensor, check wiring, address, sensor ID!"); while (1) delay(10); } iotaapOs.start(); // Start IoTaaP OS iotaapOs.startWifi(); // Connect to WiFi iotaapOs.startMqtt(callback); // Connect to MQTT broker } void loop() { // Fetch measurements from BME280 sensor float temperatureC = bme.readTemperature(); // Store temperature reading to IoTaaP Storage service, and subscribe to callback topic iotaapOs.storageServiceStore(TOKEN, "temperature", temperatureC, "/pgiIzx7n/storage/response"); delay(5000); }
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