BME280 temp/humidity/pressure sensor



  • Has anyone built a node that uses the BME280 temp/humidity/pressure sensor?

    I'm guessing if I build it from scratch, the HumiditySensor example would probably be the best one to use. One thing I saw was that someone is working on an ESP8266 weather station gateway with this sensor, and in his comments, it appears that you have to do some funky stuff with moving the CE pin somewhere else or it interferes with the I2C communication for this chip. I would be doing this on a Nano, not an ESP. Are the pin changes the same?


  • Hardware Contributor

    On the ESP8266 SDA and SCL native pins are used in the radio wiring, that's why you need the funky stuff.

    No pin changes necessary on nano or promini as A4 and A5 are not used. You plug it as any other I2C sensor (just be sure to feed it with 3.3V, not 5V)



  • Awesome. I just got it working with a test sketch like 2 minutes ago. If I get a working sketch for MySensors, how can I get it uploaded to the site as an example?

    Also, if anyone has done it before, I'd appreciate any code you might have to save some time. I only get like 5 minutes here an there to work on this.


  • Hardware Contributor

    This should work, it removes the 2-3 ESP8266 config lines:

    /**
     * The MySensors Arduino library handles the wireless radio link and protocol
     * between your home built sensors/actuators and HA controller of choice.
     * The sensors forms a self healing radio network with optional repeaters. Each
     * repeater and gateway builds a routing tables in EEPROM which keeps track of the
     * network topology allowing messages to be routed to nodes.
     *
     * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
     * Copyright (C) 2013-2015 Sensnology AB
     * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
     *
     * Documentation: http://www.mysensors.org
     * Support Forum: http://forum.mysensors.org
     *
     * This program is free software; you can redistribute it and/or
     * modify it under the terms of the GNU General Public License
     * version 2 as published by the Free Software Foundation.
     *
     *******************************
     *
     * REVISION HISTORY
     * Version 1.0 - Henrik Ekblad
     * 
     * DESCRIPTION
     * Pressure sensor example using BMP085 module  
     * http://www.mysensors.org/build/pressure
     *
     */
    
    // Enable debug prints to serial monitor
    #define MY_DEBUG 
    
    // Enable and select radio type attached
    #define MY_RADIO_NRF24
    //#define MY_RADIO_RFM69
    
    #include <SPI.h>
    #include <MySensor.h>  
    #include <Wire.h>
    
    // BME280 libraries and variables
    // Bosch BME280 Embedded Adventures MOD-1022 weather multi-sensor Arduino code
    // Written originally by Embedded Adventures
    // https://github.com/embeddedadventures/BME280
    #include <BME280_MOD-1022.h>
    
    #define BARO_CHILD 0
    #define TEMP_CHILD 1
    #define HUM_CHILD 2
    
    const float ALTITUDE = 23; // <-- adapt this value to your location's altitude (in m). Use your smartphone GPS to get an accurate value!
    
    // Sleep time between reads (in ms). Do not change this value as the forecast algorithm needs a sample every minute.
    const unsigned long SLEEP_TIME = 60000; 
    
    const char *weather[] = { "stable", "sunny", "cloudy", "unstable", "thunderstorm", "unknown" };
    enum FORECAST
    {
      STABLE = 0,     // "Stable Weather Pattern"
      SUNNY = 1,      // "Slowly rising Good Weather", "Clear/Sunny "
      CLOUDY = 2,     // "Slowly falling L-Pressure ", "Cloudy/Rain "
      UNSTABLE = 3,   // "Quickly rising H-Press",     "Not Stable"
      THUNDERSTORM = 4, // "Quickly falling L-Press",    "Thunderstorm"
      UNKNOWN = 5     // "Unknown (More Time needed)
    };
    
    float lastPressure = -1;
    float lastTemp = -1;
    float lastHum = -1;
    int lastForecast = -1;
    
    const int LAST_SAMPLES_COUNT = 5;
    float lastPressureSamples[LAST_SAMPLES_COUNT];
    
    
    // this CONVERSION_FACTOR is used to convert from Pa to kPa in the forecast algorithm
    // get kPa/h by dividing hPa by 10 
    #define CONVERSION_FACTOR (1.0/10.0)
    
    int minuteCount = 0;
    bool firstRound = true;
    // average value is used in forecast algorithm.
    float pressureAvg;
    // average after 2 hours is used as reference value for the next iteration.
    float pressureAvg2;
    
    float dP_dt;
    boolean metric;
    MyMessage tempMsg(TEMP_CHILD, V_TEMP);
    MyMessage humMsg(HUM_CHILD, V_HUM);
    MyMessage pressureMsg(BARO_CHILD, V_PRESSURE);
    MyMessage forecastMsg(BARO_CHILD, V_FORECAST);
    
    
    float getLastPressureSamplesAverage()
    {
      float lastPressureSamplesAverage = 0;
      for (int i = 0; i < LAST_SAMPLES_COUNT; i++)
      {
        lastPressureSamplesAverage += lastPressureSamples[i];
      }
      lastPressureSamplesAverage /= LAST_SAMPLES_COUNT;
    
      return lastPressureSamplesAverage;
    }
    
    
    // Algorithm found here
    // http://www.freescale.com/files/sensors/doc/app_note/AN3914.pdf
    // Pressure in hPa -->  forecast done by calculating kPa/h
    int sample(float pressure)
    {
      // Calculate the average of the last n minutes.
      int index = minuteCount % LAST_SAMPLES_COUNT;
      lastPressureSamples[index] = pressure;
    
      minuteCount++;
      if (minuteCount > 185)
      {
        minuteCount = 6;
      }
    
      if (minuteCount == 5)
      {
        pressureAvg = getLastPressureSamplesAverage();
      }
      else if (minuteCount == 35)
      {
        float lastPressureAvg = getLastPressureSamplesAverage();
        float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
        if (firstRound) // first time initial 3 hour
        {
          dP_dt = change * 2; // note this is for t = 0.5hour
        }
        else
        {
          dP_dt = change / 1.5; // divide by 1.5 as this is the difference in time from 0 value.
        }
      }
      else if (minuteCount == 65)
      {
        float lastPressureAvg = getLastPressureSamplesAverage();
        float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
        if (firstRound) //first time initial 3 hour
        {
          dP_dt = change; //note this is for t = 1 hour
        }
        else
        {
          dP_dt = change / 2; //divide by 2 as this is the difference in time from 0 value
        }
      }
      else if (minuteCount == 95)
      {
        float lastPressureAvg = getLastPressureSamplesAverage();
        float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
        if (firstRound) // first time initial 3 hour
        {
          dP_dt = change / 1.5; // note this is for t = 1.5 hour
        }
        else
        {
          dP_dt = change / 2.5; // divide by 2.5 as this is the difference in time from 0 value
        }
      }
      else if (minuteCount == 125)
      {
        float lastPressureAvg = getLastPressureSamplesAverage();
        pressureAvg2 = lastPressureAvg; // store for later use.
        float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
        if (firstRound) // first time initial 3 hour
        {
          dP_dt = change / 2; // note this is for t = 2 hour
        }
        else
        {
          dP_dt = change / 3; // divide by 3 as this is the difference in time from 0 value
        }
      }
      else if (minuteCount == 155)
      {
        float lastPressureAvg = getLastPressureSamplesAverage();
        float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
        if (firstRound) // first time initial 3 hour
        {
          dP_dt = change / 2.5; // note this is for t = 2.5 hour
        }
        else
        {
          dP_dt = change / 3.5; // divide by 3.5 as this is the difference in time from 0 value
        }
      }
      else if (minuteCount == 185)
      {
        float lastPressureAvg = getLastPressureSamplesAverage();
        float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
        if (firstRound) // first time initial 3 hour
        {
          dP_dt = change / 3; // note this is for t = 3 hour
        }
        else
        {
          dP_dt = change / 4; // divide by 4 as this is the difference in time from 0 value
        }
        pressureAvg = pressureAvg2; // Equating the pressure at 0 to the pressure at 2 hour after 3 hours have past.
        firstRound = false; // flag to let you know that this is on the past 3 hour mark. Initialized to 0 outside main loop.
      }
    
      int forecast = UNKNOWN;
      if (minuteCount < 35 && firstRound) //if time is less than 35 min on the first 3 hour interval.
      {
        forecast = UNKNOWN;
      }
      else if (dP_dt < (-0.25))
      {
        forecast = THUNDERSTORM;
      }
      else if (dP_dt > 0.25)
      {
        forecast = UNSTABLE;
      }
      else if ((dP_dt > (-0.25)) && (dP_dt < (-0.05)))
      {
        forecast = CLOUDY;
      }
      else if ((dP_dt > 0.05) && (dP_dt < 0.25))
      {
        forecast = SUNNY;
      }
      else if ((dP_dt >(-0.05)) && (dP_dt < 0.05))
      {
        forecast = STABLE;
      }
      else
      {
        forecast = UNKNOWN;
      }
    
      // uncomment when debugging
      //Serial.print(F("Forecast at minute "));
      //Serial.print(minuteCount);
      //Serial.print(F(" dP/dt = "));
      //Serial.print(dP_dt);
      //Serial.print(F("kPa/h --> "));
      //Serial.println(weather[forecast]);
    
      return forecast;
    }
    
    
    void setup() {
      metric = getConfig().isMetric;
      Wire.begin(); // Wire.begin(sda, scl)
    }
    
    void presentation()  {
      // Send the sketch version information to the gateway and Controller
      sendSketchInfo("BME280 Sensor", "1.6");
    
      // Register sensors to gw (they will be created as child devices)
      present(BARO_CHILD, S_BARO);
      present(TEMP_CHILD, S_TEMP);
      present(HUM_CHILD, S_HUM);
    }
    
    // Loop
    void loop() {
      
      // need to read the NVM compensation parameters
      BME280.readCompensationParams();
    
      /* After taking the measurement the chip goes back to sleep, use when battery powered.
      // Oversampling settings (os1x, os2x, os4x, os8x or os16x).
      BME280.writeFilterCoefficient(fc_16);       // IIR Filter coefficient, higher numbers avoid sudden changes to be accounted for (such as slamming a door)
      BME280.writeOversamplingPressure(os16x);    // pressure x16
      BME280.writeOversamplingTemperature(os8x);  // temperature x8
      BME280.writeOversamplingHumidity(os8x);     // humidity x8
    
      BME280.writeMode(smForced);                 // Forced sample.  After taking the measurement the chip goes back to sleep
      */
    
      // Normal mode for regular automatic samples
      BME280.writeStandbyTime(tsb_0p5ms);         // tsb = 0.5ms
      BME280.writeFilterCoefficient(fc_16);       // IIR Filter coefficient 16
      BME280.writeOversamplingPressure(os16x);    // pressure x16
      BME280.writeOversamplingTemperature(os8x);  // temperature x8
      BME280.writeOversamplingHumidity(os8x);     // humidity x8
      
      BME280.writeMode(smNormal);
      
      while (1) {
        // Just to be sure, wait until sensor is done mesuring  
        while (BME280.isMeasuring()) {
      }
      
      // Read out the data - must do this before calling the getxxxxx routines
      BME280.readMeasurements();
    
      float temperature = BME280.getTemperatureMostAccurate();                    // must get temp first
      float humidity = BME280.getHumidityMostAccurate();
      float pressure_local = BME280.getPressureMostAccurate();                    // Get pressure at current location
      float pressure = pressure_local/pow((1.0 - ( ALTITUDE / 44330.0 )), 5.255); // Adjust to sea level pressure using user altitude
      int forecast = sample(pressure);
      
      if (!metric) 
      {
        // Convert to fahrenheit
        temperature = temperature * 9.0 / 5.0 + 32.0;
      }
    
      Serial.println();
      Serial.print("Temperature = ");
      Serial.print(temperature);
      Serial.println(metric ? " °C" : " °F");
      Serial.print("Humidity = ");
      Serial.print(humidity);
      Serial.println(" %");
      Serial.print("Pressure = ");
      Serial.print(pressure);
      Serial.println(" hPa");
      Serial.print("Forecast = ");
      Serial.println(weather[forecast]);
      Serial.println();
    
    
      if (temperature != lastTemp) 
      {
        send(tempMsg.set(temperature, 1));
        lastTemp = temperature;
      }
    
    
      if (humidity != lastHum) 
      {
        send(humMsg.set(humidity, 1));
        lastHum = humidity;
      }
    
      if (pressure != lastPressure) 
      {
        send(pressureMsg.set(pressure, 2));
        lastPressure = pressure;
      }
    
      if (forecast != lastForecast)
      {
        send(forecastMsg.set(weather[forecast]));
        lastForecast = forecast;
      }
      
      sleep(SLEEP_TIME);
      
    }
    }```


  • @signal15
    I have this sensor working on Arduino Mini Pro. I am sure you can make it work under ESP8266



  • @emc2

    I'm getting some problems compiling the code you provided above. Is this for 1.6 or something? I'm on 1.5, do I need to change some function names?

    Arduino/Mysensors_BME280/Mysensors_BME280.ino: In function 'void setup()':
    Mysensors_BME280:252: error: 'getConfig' was not declared in this scope
       metric = getConfig().isMetric;
                          ^
    /Users/jay.austad/Documents/Arduino/Mysensors_BME280/Mysensors_BME280.ino: In function 'void presentation()':
    Mysensors_BME280:258: error: 'sendSketchInfo' was not declared in this scope
       sendSketchInfo("BME280 Sensor", "1.6");
                                            ^
    Mysensors_BME280:261: error: 'present' was not declared in this scope
       present(BARO_CHILD, S_BARO);
                                 ^
    /Users/jay.austad/Documents/Arduino/Mysensors_BME280/Mysensors_BME280.ino: In function 'void loop()':
    Mysensors_BME280:328: error: 'send' was not declared in this scope
         send(tempMsg.set(temperature, 1));
                                         ^
    Mysensors_BME280:335: error: 'send' was not declared in this scope
         send(humMsg.set(humidity, 1));
                                     ^
    Mysensors_BME280:341: error: 'send' was not declared in this scope
         send(pressureMsg.set(pressure, 2));
                                          ^
    Mysensors_BME280:347: error: 'send' was not declared in this scope
         send(forecastMsg.set(weather[forecast]));
                                                ^
    Mysensors_BME280:351: error: 'sleep' was not declared in this scope
       sleep(SLEEP_TIME);
                       ^
    exit status 1
    'getConfig' was not declared in this scope```


  • Ah, looks like I just need to add "gw." in front of all of these functions and "MySensor gw;" just after the includes.


  • Hardware Contributor

    Ah yes sorry, it's for the dev branch (1.6 or now called 2.0)



  • @emc2

    Eh, looks like there's a lot more that I have to do to get this working, like moving the presentation into the setup() function.


  • Hardware Contributor

    If you are using 1.5 probably a lot more.

    Easier to install 2.0, compile and upload. It will be compatible with your 1.5 gateway anyway.



  • @emc2

    Oh, I thought that you had to upgrade the gateway as well. If that's the case, then I'll grab 2.0. Do I just go to the dev branch in github and hit download ZIP?



  • Do you have to upgrade the files on the controller to 2.0b as well? I have a vera, and when I added this new sensor on 2.0b, all of my nodes stopped updating and the tiles for them on the Devices screen doesn't list anything about the sensor like it normally does.

    I get these errors in the Vera logs:

    02	05/06/16 18:54:40.167	Device_Service::MatchupUpnpServices no upnp service for urn:upnp-arduino-cc:serviceId:arduino1 <0x2ac17000>
    02	05/06/16 18:54:40.170	Device_Service::MatchupUpnpServices no upnp service for urn:upnp-arduino-cc:serviceId:arduinonode1 <0x2ac17000>
    02	05/06/16 18:54:40.171	Device_Service::MatchupUpnpServices no upnp service for urn:upnp-arduino-cc:serviceId:arduinonode1 <0x2ac17000>```
    

    Also, the MySensors parent device disappeared from my Devices page in Vera. If I telnet to my gateway on port 5003, I only see the new sensor reporting as well, not any of my other sensors. Did the 2.0b sensor do something bad to my gateway or the Vera plugin?

    Update: I deleted the new devices created from the 2.0b sensor in my Vera. This fixed it so the other node information showed up again, and the MySensors parent device showed up. But, my 1.5 sensors were no longer updating. I restarted them, and they started updating.

    If 2.0 sensors are designed to be backwards compatible with a 1.5 gateway and 1.5 controller code, then there's a problem somewhere. Maybe it's with the Vera code. But, like I said, I telneted to port 5003 on my gateway, and the only thing that the gateway was receiving was the data from my 2.0b sensor. Either the gateway was ignoring the 1.5 sensors, or the 1.5 sensors stopped sending for some reason.

    Thoughts?


  • Admin



  • @hek

    Let me know if you make a change and need me to test.



  • @emc2 or anybody:

    Does anyone have a working BME280 mysensors arduino sketch? The code above states include mysensor.h now it is mysensorS.h, so I have renamed, but it won't compile, it says:

    In function 'void setup()':
    
    bme280:252: error: 'getConfig' was not declared in this scope
    

    I have a MySensors Gateway USB
    Version: 2.1.1 (arduino nano) with Domoticz, and I would like to use the bme280 for a battery powered outdoor temp/humidity/barometer (as DHT22 does not like battery level below 3.3V, and I would run on 2x1.5V AA)

    Thanks


  • Hardware Contributor

    Was modified in 2.1.1, you need to change

    metric = getConfig().isMetric;
    

    to

    metric = getControllerConfig().isMetric;  // was getConfig().isMetric; before MySensors v2.1.1
    


  • Still a lot of errors in this sketch, did take some out but this is still in it:

    In file included from C:\Users\x\Documents\Arduino\BME280_sensor\BME280_sensor.ino:48:0:

    C:\Users\x\Documents\Arduino\libraries\BME280/BME280_MOD-1022.h:41:21: warning: extra tokens at end of #ifndef directive

    #ifndef __BME280_MOD-1022_H

                     ^
    

    C:\Users\x\Documents\Arduino\libraries\BME280/BME280_MOD-1022.h:42:21: warning: ISO C99 requires whitespace after the macro name

    #define __BME280_MOD-1022_H

                     ^
    

    In file included from C:\Users\x\Documents\Arduino\libraries\BME280\BME280_MOD-1022.cpp:40:0:

    C:\Users\x\Documents\Arduino\libraries\BME280\BME280_MOD-1022.h:41:21: warning: extra tokens at end of #ifndef directive

    #ifndef __BME280_MOD-1022_H

                     ^
    

    C:\Users\x\Documents\Arduino\libraries\BME280\BME280_MOD-1022.h:42:21: warning: ISO C99 requires whitespace after the macro name

    #define __BME280_MOD-1022_H

                     ^
    

    C:\Users\x\Documents\Arduino\libraries\BME280\BME280_MOD-1022.cpp: In member function 'BME280Class::readCompensationParams()':

    C:\Users\x\Documents\Arduino\libraries\BME280\BME280_MOD-1022.cpp:276:45: warning: iteration 20 invokes undefined behavior [-Waggressive-loop-optimizations]

    compParams.compArray[count] = Wire.read();
    
                                             ^
    

    C:\Users\x\Documents\Arduino\libraries\BME280\BME280_MOD-1022.cpp:275:3: note: containing loop

    for (count = 0; count < 28; count++) { // first 28 bytes we can process like this

    ^

    C:\Users\x\Documents\Arduino\BME280_sensor\BME280_sensor.ino: In function 'loop':

    C:\Users\x\Documents\Arduino\libraries\BME280\BME280_MOD-1022.cpp:276:45: warning: iteration 20 invokes undefined behavior [-Waggressive-loop-optimizations]

    compParams.compArray[count] = Wire.read();
    
                                             ^
    

    C:\Users\x\Documents\Arduino\libraries\BME280\BME280_MOD-1022.cpp:275:3: note: containing loop

    for (count = 0; count < 28; count++) { // first 28 bytes we can process like this



  • @emc2 Thanks! With this modification the sketch compiled successfully. Today I had time, so put everything together, and the BME280 works with the 2.4GH radio, temp/hum/pressure all reporting like they should.

    Using arduino pro mini, bme280, nrf24, 2XAA Batteries. It reports to the mysensors serial gw, and then shown in domoticz.



  • @yoshida Hello
    You can share your sketch.
    Please
    I can not make modifications.
    I still have a lot of errors.



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