Multiple BME80 on arduino

Projects Programming
1

Hello, I working on a project back in the beginning of 2024 a multiple temperature logger using the bme680 on i2c. I had to put it on hold and forgot all about it. I just went recently went through some of my files and saw it. The problem I'm having back then is the second sensor. I couldn't figure out how to get it running because of the library. I found the adafruit library for the bme680 here https://github.com/adafruit/Adafruit_BME680 It works but I there is no example on how I can display the second sensor. Or how to address it. Then I found out I need to attach the SD0 to ground to get the second address.

Once I did that I used an i2c scanner and saw both sensors. It still brings me back to how to get the second sensor working. I searched online for a long time. I couldn't find an example or figure it out how to get it woeking back than.

I'm here once again asking for help on how I can get it to work. Please help me?

Joseph

2

I haven't looked at the library in detail. But, I'd suggest instantiating a second Adafruit_BME680 object and provide it's I2C address in the begin() function. See Adafruit_BME680.h:

  bool begin(uint8_t addr = BME68X_DEFAULT_ADDRESS, bool initSettings = true);
3

@gfvalvo I did take a look at the library and before I was able to change it manuslly in the library to test.

4

There's no need to change the library. Just supply the second address as an argument to the begin() function.

5

@gfvalvo Just a quick update. I wasn't able to get it working I went throught the datasheet and library. I guess My still lack of skills somehow I couldn't figure it out. And searching online leed me to nowhere. However I did manage to find this on github after searching over 200 sites trying to figure this out. A library that has an example with both sensors on it here https://github.com/sparkfun/SparkFun_BME280_Arduino_Library/tree/V_1.2.0 it's an older library. However it does work and I did manage to get both sensors working.

well not at first it was seeing the first one but not the sensor one. And I didn't know why. I looked at all my wiring and it looked good. I looked over the example code and that looked good. I even learned a little from it on how to grab the sensor sensor and how to set it up in the settings which I didn''t know. Now I do know. But I couldn't get it to display a second sensor. Turns out that it was my fault.

I have both sensors set to 0x76 instead of one being 0x76 and second one being 0x77. I put botgh SD0 to ground at the same time. Now I corrected that and I can now see both sensors with no problem.

Thank you @gfvalvo for all the help and information. And also to the community for the great work in here.

Joseph

6

If you're interested, you can post your attempt at making it work. Forum members will provide assistance. We can't help you if you don't post the code.

7

Hello, @gfvalvo I went back to the original cde because I was having problems. I'm trying to change the address for the i2c from 0x77 to 0x76. I added in the setup bme.begin(0x76); in the beginning and in serial monitor says BME680 testCould not find a valid BME680 sensor, check wiring! Not sure why it wouldn't change here. Adding the sktch in here. Not sure what to do to change it to see the other sensor?

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_BME680.h"

#define BME_SCK 13
#define BME_MISO 12
#define BME_MOSI 11
#define BME_CS 10

#define SEALEVELPRESSURE_HPA (1013.25)

Adafruit_BME680 bme; // I2C
//Adafruit_BME680 bme(BME_CS); // hardware SPI
//Adafruit_BME680 bme(BME_CS, BME_MOSI, BME_MISO,  BME_SCK);

void setup() {
  bme.begin(0x76);
  Serial.begin(9600);
  while (!Serial);
  Serial.println(F("BME680 test"));

  if (!bme.begin()) {
    Serial.println("Could not find a valid BME680 sensor, check wiring!");
    while (1);
  }

  // Set up oversampling and filter initialization
  bme.setTemperatureOversampling(BME680_OS_8X);
  bme.setHumidityOversampling(BME680_OS_2X);
  bme.setPressureOversampling(BME680_OS_4X);
  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
  bme.setGasHeater(320, 150); // 320*C for 150 ms
}

void loop() {
  if (! bme.performReading()) {
    Serial.println("Failed to perform reading :(");
    return;
  }
  Serial.print("Temperature = ");
  Serial.print(bme.temperature);
  Serial.println(" *C");

  Serial.print("Pressure = ");
  Serial.print(bme.pressure / 100.0);
  Serial.println(" hPa");

  Serial.print("Humidity = ");
  Serial.print(bme.humidity);
  Serial.println(" %");

  Serial.print("Gas = ");
  Serial.print(bme.gas_resistance / 1000.0);
  Serial.println(" KOhms");

  Serial.print("Approx. Altitude = ");
  Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
  Serial.println(" m");

  Serial.println();
  delay(2000);
}

However if i change it in the library and take out that bme.begin(0x76); in setup then It can see the sensor.

8

Did you get both BME680s to work together?
You can change the BME680 i2c address with the SDO pin.

9

@SurferTim Yes I have the SD0 to ground. If I change it in the library it can see the 0x76 but if I add the bme.begin(0x76); in the setup it doesn't see it.

10

If you want to use 2 on the same i2c bus, connect one device SDO to GND and the other to V+.
One will show as 0x76 and the other 0x77.

11

at the moment I'monly using one sensor for testing. I only have one wired up. and put the sd0 to ground. When I finish testing this then I'll wire up a second ine. But for now I can not address this one correctly in setup.

12

Did you use the i2c_scanner sketch to determine if the BME680 is at the i2c address you think it is?

13

i2c scanner says.

I2C Scanner
Scanning...
I2C device found at address 0x76 !
done

its there and working. again if I change it in the library it works with no ptoblem But if I address it in the setup with bme.begin(0x76); it doesn't see it. It wants to revert back to that 0x77 address.

14

The library uses 0x77 as the default.
Try this in setup.
bme.begin(addr = 0x76);

15

@SurferTim 'addr' was not declared in this scope.

16

Try this:
bme.begin(0x76,true);

17

@SurferTim Same thing. BME680 testCould not find a valid BME680 sensor, check wiring! but this time no error.

18

The example shows a different way to declare the bme instance.
Adafruit_BME680 bme(&Wire); // I2C

19

@SurferTim Yes this is strange. I'm notr sure how to address it like it needs to be.

20

You are using this in your sketch.
Adafruit_BME680 bme; // I2C
This is what the examples use.
Adafruit_BME680 bme(&Wire); // I2C