The ESP8266 is a $5 IOT device with huge capabilities. In this post we will log data to a remote Influx database running on a RaspberryPi.

I am programming the ESP8266 in the Arduino IDE, the ESP8266 library is required, you can find it here. I have a test code file (of copy from below) that you can upload after entering your InfluxDB I.P. Address, SSID & Password and it will start logging data immediately.

Code for InfluxDB Version 1.x (Version 1.6 specifically for me.)

#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include <InfluxDb.h>

#define INFLUXDB_HOST "192.168.1.1"   //Enter IP of device running Influx Database
#define WIFI_SSID "SSID"              //Enter SSID of your WIFI Access Point
#define WIFI_PASS "PASSWORD"          //Enter Password of your WIFI Access Point

ESP8266WiFiMulti WiFiMulti;
Influxdb influx(INFLUXDB_HOST);

void setup() {
  Serial.begin(9600);
  WiFiMulti.addAP(WIFI_SSID, WIFI_PASS);
  Serial.print("Connecting to WIFI");
  while (WiFiMulti.run() != WL_CONNECTED) {
    Serial.print(".");
    delay(100);
  }
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

  influx.setDb("esp8266_test");

  Serial.println("Setup Complete.");
}

int loopCount = 0;

void loop() {
  loopCount++;

  InfluxData row("data");
  row.addTag("Device", "ESP8266");
  row.addTag("Sensor", "Temp");
  row.addTag("Unit", "Celsius");
  row.addValue("LoopCount", loopCount);
  row.addValue("RandomValue", random(10, 40));

  influx.write(row);
  delay(5000);
}

Code for InfluxDB Version 2.x (Version 2.1 specifically for me). Download Arduino library from here.

#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include <InfluxDb.h>

#define INFLUXDB_URL "http://192.168.1.XXX:8086" // e.g. http://192.168.1.48:8086 (In InfluxDB 2 UI -> Load Data -> Client Libraries), 
#define INFLUXDB_TOKEN "YOUR_TOKEN" // InfluxDB 2 server or cloud API authentication token (Use: InfluxDB UI -> Load Data -> Tokens -> <select token>)
#define INFLUXDB_ORG "influx" // InfluxDB 2 organization id (Use: InfluxDB UI -> Settings -> Profile -> <name under tile> )
#define INFLUXDB_BUCKET "YOUR_BUCKET" // InfluxDB 2 bucket name (Use: InfluxDB UI -> Load Data -> Buckets)
#define WIFI_SSID "YOUR_SSID"
#define WIFI_PASS "YOUR_PASS"
#define MEASUREMENT "esp"
#define DEVICE "esp_04"
#define ID "Development ESP"

ESP8266WiFiMulti WiFiMulti;
InfluxDBClient client(INFLUXDB_URL, INFLUXDB_ORG, INFLUXDB_BUCKET, INFLUXDB_TOKEN);
Point row(MEASUREMENT); // Setup InfluxDB data point

void setup() {
  Serial.begin(9600);
  WiFiMulti.addAP(WIFI_SSID, WIFI_PASS);
  Serial.print("Connecting to WIFI");
  while (WiFiMulti.run() != WL_CONNECTED) {
    Serial.print(".");
    delay(100);
  }
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

  if (client.validateConnection()) {          // Checks if can communicate with InfluxDB server
      Serial.print("Connected to InfluxDB: ");
      Serial.println(client.getServerUrl());
  }
  else {
      Serial.print("InfluxDB connection failed: ");
      Serial.println(client.getLastErrorMessage());
  }

  Serial.println("Setup Complete.");
}

int loopCount = 0;

void loop() {
  loopCount++;

  row.clearFields();  // Clear Influx Fields
  row.clearTags();    // Clear Influx Tags
  row.addTag("Device", DEVICE);
  row.addTag("ID", ID);
  row.addField("LoopCount", loopCount);
  row.addField("RandomValue", random(0, 100)); //Helpful for debugging if needed.
  row.addField("25_Value", 20);
  row.addField("50_Value", 50); 
  row.addField("100_Value", 100);     

  Serial.print("Writing: "); // Print what are we exactly writing
  Serial.println(client.pointToLineProtocol(row));

      if (!client.writePoint(row)) {
        Serial.print("InfluxDB write failed: ");
        Serial.println(client.getLastErrorMessage());
      }
      else {
      Serial.println("Wrote data successfully");
      Serial.println("");
      }
  delay(5000);
}

The Arduino Serial Terminal will display something like the below so you can if it is working. (My previous tutorial shows setting up InfluxDB, ensure you have the database “esp8266_test” created as we are going to write to that.)

 --> writing to esp8266_test:
data,Device=ESP8266,Sensor=Temp,Unit=Celsius LoopCount=256.00,RandomValue=37.00
 <-- Response: 204 ""
 --> writing to esp8266_test:
data,Device=ESP8266,Sensor=Temp,Unit=Celsius LoopCount=257.00,RandomValue=20.00
 <-- Response: 204

On the Influx Database we can look at the data by:

influx
USE esp8266_test
select * from data limit 50

Below you can see the export from my database (I have shortened the time field for neatness). You can see I reset the ESP8266 a couple of times due to the LoopCount value.

time        Device  LoopCount RandomValue Sensor Unit    
----        ------  --------- ----------- ------ ----   
52808175073 ESP8266 1         38          Temp   Celsius                              
63108846141 ESP8266 2         35          Temp   Celsius                              
69802517277 ESP8266 1         13          Temp   Celsius                              
79892112240 ESP8266 2         12          Temp   Celsius                              
89961602267 ESP8266 3         14          Temp   Celsius                              
99998928411 ESP8266 4         22          Temp   Celsius                              
10053683452 ESP8266 5         10          Temp   Celsius                              
20120378415 ESP8266 6         28          Temp   Celsius                              
30175745403 ESP8266 7         14          Temp   Celsius                              
40732248123 ESP8266 8         38          Temp   Celsius                              
51232948067 ESP8266 9         15          Temp   Celsius                              
61322347831 ESP8266 10        13          Temp   Celsius                              
71424432515 ESP8266 11        19          Temp   Celsius                              
84740185749 ESP8266 1         18          Temp   Celsius                              
94790343615 ESP8266 2         21          Temp   Celsius                              
04839215465 ESP8266 3         13          Temp   Celsius                              
31864448941 ESP8266 1         32          Temp   Celsius                              
41956355523 ESP8266 2         36          Temp   Celsius                              
52018136222 ESP8266 3         30          Temp   Celsius                              
62083037888 ESP8266 4         22          Temp   Celsius       

That’s it!

Resources I used:

• https://github.com/davidgs/ESP8266_Influx_DB_V2
• https://www.influxdata.com/blog/writing-data-from-arduino-to-influxdb-v2/