NodeMCU BMP180
Updated: Dec 4, 2021

#include <SFE_BMP180.h>
#include <Wire.h>
#include <ESP8266WiFi.h> //The library we will use for the wifi connection
#include <PubSubClient.h> // The library we will use for the mqtt connection
//mqtt connection library settings
WiFiClient espClient;
PubSubClient client(espClient);
//
//settings for internet and mqtt connection
const char* ssid = ""; // wifi SSID
const char* password = ""; // wifi password
const char* mqttServer = ""; // mqtt server ip to be sent by smartespiot by mail
const int mqttPort = ; // mqtt port to be sent by smartespiot by mail
const char* mqttUser = ""; // mqtt username to be sent by smartespiot by mail
const char* mqttPassword = ""; // mqtt pass to be sent by smartespiot by mail
//
SFE_BMP180 pressure;
double baseline; // baseline pressure
void setup()
{
Serial.begin(9600);
Wire.begin(14, 12); // d6-14 scl d5-12 sda
Serial.println("REBOOT");
// Initialize the sensor (it is important to get calibration values stored on the device).
if (pressure.begin())
Serial.println("BMP180 init success");
else
{
// Oops, something went wrong, this is usually a connection problem,
// see the comments at the top of this sketch for the proper connections.
Serial.println("BMP180 init fail (disconnected?)\n\n");
while (1); // Pause forever.
}
// Get the baseline pressure:
baseline = getPressure();
Serial.print("baseline pressure: ");
Serial.print(baseline);
Serial.println(" mb");
WiFi.begin(ssid, password); // start the wifi connection process
while (WiFi.status() != WL_CONNECTED) { //
delay(500); //wait 500ms
Serial.println("Connecting to wifi..."); // wait until the wifi process connects
}
Serial.println("Wifi connection ready :)"); // print the connection made information to the serial port
client.setServer(mqttServer, mqttPort);//start connecting to the mqtt server from the specified port
while (!client.connected()) { //wait until we connect to mqtt
Serial.println("Connecting to MQTT server...");
if (client.connect("SmartEspIOT", mqttUser, mqttPassword )) {//login to mqtt server with username and password with smartespIOT name
Serial.println("MQTT connection established :) ");
} else {
Serial.print("Unable to connect... ");// If the connection cannot be established, let's give a warning
Serial.print(client.state()); // print the problem description
// We can understand the problem according to the information returned from the clients state.
//-4 : MQTT_CONNECTION_TIMEOUT - the server did not respond in the ongoing time
//-3 : MQTT_CONNECTION_LOST - network connection lost
//-2 : MQTT_CONNECT_FAILED - network connection failed
//-1 : MQTT_DISCONNECTED - disconnected
//0 : MQTT_CONNECTED - connection established
//1 : MQTT_CONNECT_BAD_PROTOCOL - The server does not support the requested MQTT version
//2 : MQTT_CONNECT_BAD_CLIENT_ID - The server did not accept your information
//3 : MQTT_CONNECT_UNAVAILABLE - The server did not accept the connectionetmed
//4 : MQTT_CONNECT_BAD_CREDENTIALS - username password not accepted
//5 : MQTT_CONNECT_UNAUTHORIZED - you are not authorized to connect
delay(2000); // wait two seconds and try connecting again
}
}
}
void loop()
{
double a, P;
// Get a new pressure reading:
P = getPressure();
// Show the relative altitude difference between
// the new reading and the baseline reading:
a = pressure.altitude(P, baseline);
Serial.print("relative altitude: ");
if (a >= 0.0) Serial.print(" "); // add a space for positive numbers
Serial.print(a, 1);
Serial.print(" meters, ");
if (a >= 0.0) Serial.print(" "); // add a space for positive numbers
Serial.print(a * 3.28084, 0);
Serial.println(" feet");
//Publish message ///
client.publish("devicename/meters", String(a).c_str());// send meters
client.publish("devicename/feet", String(a * 3.28084).c_str());// send feed
delay(2000); // wait two seconds and send the message again
//
}
double getPressure()
{
char status;
double T, P, p0, a;
// You must first get a temperature measurement to perform a pressure reading.
// Start a temperature measurement:
// If request is successful, the number of ms to wait is returned.
// If request is unsuccessful, 0 is returned.
status = pressure.startTemperature();
if (status != 0)
{
// Wait for the measurement to complete:
delay(status);
// Retrieve the completed temperature measurement:
// Note that the measurement is stored in the variable T.
// Use '&T' to provide the address of T to the function.
// Function returns 1 if successful, 0 if failure.
status = pressure.getTemperature(T);
if (status != 0)
{
// Start a pressure measurement:
// The parameter is the oversampling setting, from 0 to 3 (highest res, longest wait).
// If request is successful, the number of ms to wait is returned.
// If request is unsuccessful, 0 is returned.
status = pressure.startPressure(3);
if (status != 0)
{
// Wait for the measurement to complete:
delay(status);
// Retrieve the completed pressure measurement:
// Note that the measurement is stored in the variable P.
// Use '&P' to provide the address of P.
// Note also that the function requires the previous temperature measurement (T).
// (If temperature is stable, you can do one temperature measurement for a number of pressure measurements.)
// Function returns 1 if successful, 0 if failure.
status = pressure.getPressure(P, T);
if (status != 0)
{
return (P);
}
else Serial.println("error retrieving pressure measurement\n");
}
else Serial.println("error starting pressure measurement\n");
}
else Serial.println("error retrieving temperature measurement\n");
}
else Serial.println("error starting temperature measurement\n");
}
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