💬 Atmospheric Pressure Sensor

[ghislain]

Hi, i'm using this sketch and I had to modify it a little bit. But i'm at work and i haven't it.

You defined the altitude to 688 meters in you sketch, are you sure, you said you're at 1014mbars. If you're really at 700m you should be near 930mbars not 1014mbars.

[James Flosse]

Ok i defined the altitude by my own (225 meters) but i have the same pressure and temperature :S

[ghislain]

Too bad, can you upload a basic example sketch in the library adafruit to read pressure and temperature, just to be sure there is the same behavior.

[James Flosse]

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP085_U.h>
   
Adafruit_BMP085_Unified bmp = Adafruit_BMP085_Unified(10085);
 
void setup(void) 
{
  Serial.begin(9600);
  Serial.println("Pressure Sensor Test"); Serial.println("");
  
  /* Initialise the sensor */
  if(!bmp.begin())
  {
    /* There was a problem detecting the BMP085 ... check your connections */
    Serial.print("Ooops, no BMP085 detected ... Check your wiring or I2C ADDR!");
    while(1);
  }
}
 
void loop(void) 
{
  /* Get a new sensor event */ 
  sensors_event_t event;
  bmp.getEvent(&event);
 
  /* Display the results (barometric pressure is measure in hPa) */
  if (event.pressure)
  {
    /* Display atmospheric pressure in hPa */
    Serial.print("Pressure: "); Serial.print(event.pressure); Serial.println(" hPa");
  }
  else
  {
    Serial.println("Sensor error");
  }
  delay(250);
}

Pressure: 756.46 hPa
Pressure: 756.47 hPa
Pressure: 756.49 hPa
Pressure: 756.44 hPa
Pressure: 756.44 hPa
Pressure: 756.46 hPa
Pressure: 756.41 hPa
Pressure: 756.44 hPa
Pressure: 756.42 hPa
Pressure: 756.39 hPa
Pressure: 756.42 hPa
Pressure: 756.44 hPa
Pressure: 756.38 hPa
Pressure: 756.40 hPa
Pressure: 756.41 hPa
Pressure: 756.38 hPa
Pressure: 756.41 hPa
Pressure: 756.40 hPa
Pressure: 756.38 hPa
Pressure: 756.40 hPa
Pressure: 756.42 hPa
Pressure: 756.34 hPa
Pressure: 756.22 hPa
Pressure: 756.33 hPa
Pressure: 756.37 hPa
Pressure: 756.38 hPa

same pressure

[ghislain]

Where did you buy your bmp180 ? you said the 3 you have make the same behavior ? something is wrong with the BMP sensor.

[James Flosse]

I bought it in banggood, but it work's before...

[ghislain]

It worked for a while and now it doesn't ? no problem of power supply ? 3v3 ?

[James Flosse]

I supply itwith the 3.3 V output off arduino

[ghislain]

I supply it with 5v, are you sure it's a 3v3 version ?

[James Flosse]

i tested with 3.3V and 5volt but same result
http://www.banggood.com/fr/GY-68-BMP180-Digital-Barometric-Pressure-Sensor-Board-Module-p-1059025.html?rmmds=myorder

[ghislain]

OK, i've no further idea to help you. But i think your sensor is dead. DId you try older or newer library to compile your project ?

[James Flosse]

Have you link for older library? Are you french?

[ghislain]

I am and you ? I can give you the sketch which is working for me with library i used.

[James Flosse]

Yes ^^ . can you give me at snyp_thx at hotmail dot fr?

[bgunnarb]

Hi!
I had exactly the same problem until I realised I had compiled for the 8 MHz version of the Arduino Pro Mini instead of the 16 MHz version.
Also, recently building an humidity sensor I realised there are no pull-up resistors on the SDA SDL lines, but that should be built-in if you use a break-out module.

[Heinz]

Which altitude did you enter, or at which sealevel do you live (in meters)?

const float ALTITUDE = 688; // <-- adapt this value to your own location's altitude.

The pressure of 728 hPa is a bit strange as it should be around 1000 hPa. In my eyes you threw out the code to correct the pressure depending on the sealevel of your home. See the code from my sketch:

float pressure = bmp.seaLevelForAltitude(SEALEVEL, absolutePressure);

Here you can download the sketch I am using:
https://github.com/windkh/mysensors/blob/master/WeatherStationSensor/WeatherStationSensor.ino

The forecast will be unknown for at least 30minutes, because the sensor needs that time to detect a weather trend.

[James Flosse]

@bgunnarb you are find the problem, i think i have arduino pro mini 3.3V but it's 5V. Thx very much it's work better now :)

[Jeff Willecke]

Where do the pin assignments live?

[gohan]

@Jeff-Willecke
in the article page
SCL A5 (analog input) Marked blue
SDA A4 (analog input) Marked green

[Jeff Willecke]

@gohan it appears as though I need SLC and SDA for the sensor it will prevent me from using a second SLC/SDA device. I was assuming that they were utilizing the analog input. My comment may be deleted as it is clearly not applicable