How To use the Kalman filter with the BMP280?

[sszabo]

Hello ...
I recently started to use the BMP280 for measuring pressure Temp and ALTITUDE. The main goal is to measure altitude. I can measure altitude with the example sketch with the BMP280 libary. But it is not accurate and has noise interruption. I have seen people use the "Kalman" filter with sensors like the BMP280. I also am using the MPU6050 if that is necessary to calculate Altitude. If anyone would like to get back to me that would be very helpful.

CODE

bmp280test.ino (2.0 KB)

Regards

[jremington]

For a one dimensional measurement like pressure or altitude, simple averaging of N measurements, or an exponential moving average filter is all you need.

The 1D Kalman filter is equivalent to an exponential filter average.

[TomGeorge]

Hi, @sszabo
To add code please click this link;

How to get the best out of this forum

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Thanks.. Tom...

[mrburnette]

Kalman Filter Lib:

https://www.arduino.cc/reference/en/libraries/kalman-filter-library/

[sszabo]

Thanks for the replies, I'm sorry, I am pretty new to the forum. Anyway I have seen kalman library but I don't know how to implement that into the BMP280 sketch.

/***************************************************************************
  This is a library for the BMP280 humidity, temperature & pressure sensor

  Designed specifically to work with the Adafruit BMP280 Breakout
  ----> http://www.adafruit.com/products/2651

  These sensors use I2C or SPI to communicate, 2 or 4 pins are required
  to interface.

  Adafruit invests time and resources providing this open source code,
  please support Adafruit andopen-source hardware by purchasing products
  from Adafruit!

  Written by Limor Fried & Kevin Townsend for Adafruit Industries.
  BSD license, all text above must be included in any redistribution
 ***************************************************************************/

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_BMP280.h>

#define BMP_SCK  (13)
#define BMP_MISO (12)
#define BMP_MOSI (11)
#define BMP_CS   (10)

Adafruit_BMP280 bmp; // I2C
//Adafruit_BMP280 bmp(BMP_CS); // hardware SPI
//Adafruit_BMP280 bmp(BMP_CS, BMP_MOSI, BMP_MISO,  BMP_SCK);

void setup() {
  Serial.begin(9600);
  Serial.println(F("BMP280 test"));

  //if (!bmp.begin(BMP280_ADDRESS_ALT, BMP280_CHIPID)) {
  if (!bmp.begin()) {
    Serial.println(F("Could not find a valid BMP280 sensor, check wiring or "
                      "try a different address!"));
    while (1) delay(10);
  }

  /* Default settings from datasheet. */
  bmp.setSampling(Adafruit_BMP280::MODE_NORMAL,     /* Operating Mode. */
                  Adafruit_BMP280::SAMPLING_X2,     /* Temp. oversampling */
                  Adafruit_BMP280::SAMPLING_X16,    /* Pressure oversampling */
                  Adafruit_BMP280::FILTER_X16,      /* Filtering. */
                  Adafruit_BMP280::STANDBY_MS_500); /* Standby time. */
}

void loop() {
    Serial.print(F("Temperature = "));
    Serial.print(bmp.readTemperature());
    Serial.println(" *C");

    Serial.print(F("Pressure = "));
    Serial.print(bmp.readPressure());
    Serial.println(" Pa");

    Serial.print(F("Approx altitude = "));
    Serial.print(bmp.readAltitude(1013.25)); /* Adjusted to local forecast! */
    Serial.println(" m");

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

Thakyou ...

[jremington]

@sszabo

I don't know how to implement that into the BMP280 sketch

No need to bother. You really can't do much better than adding up (for example) 100 measurements and dividing by 100. There is absolutely no advantage to using a Kalman filter for such a simple task.

If you are learning to program, start simply and work your way up!

[sszabo]

so.....
what can i do??

[sszabo]

I verify the code of kalman.cpp and it comes up with the error "'Kalman' does not name a type; did you mean 'Kalman_h'?"

Any solutions?
Thanks in advance
`

[JohnRob]

I've not used the Kalman filter but I know the folks who have answered and I very sure they are correct.

An important question; how often are your reading the BMP and how fast do you need to have filtered data?
For instance, measuring altitude of a model rocket will have different needs than measuring altitude for a dirt biker.

Another Hint. If your drive to use the Kalman filter is because your not good at coding and don't know where to start a simple averaging filter. That is a different question. You should start a new thread or at least state your current situation.

[sszabo]

Ok thanks @JohnRob I am pretty good at programming but I get confused about certain things. I should probably start slower but I’ll do some research.

[sszabo]

Every 500 milliseconds I want to log dyne data.

[JohnRob]

OK that's fine but do you know how fast you can measure the BMP-280? Can you disable the temperature and humidity measurement to speed up the repetition rate of the Pressure sensor portion?

Its been a long time but I seem to recall 1/2 second is near the max measurement rate for this sensor. If this is true, will not be able to filter your data.

[mrburnette]

I think this may answer your need:

https://www.rocketryforum.com/threads/arduino-altimeter-bmp280-inbuilt-noise-filtering-settings.151941/

[LarryD]

Hi @mrburnette haven’t seen you around here for a while.

Welcome back !

[mrburnette]

Hi, LarryD...
Off in Raspberry land and STM32duino world... think maybe 3 or 4 years! Spent the last 6 mo. with C on a TI CC2533 just to get back into thinking low-level. Sometimes I just feel the need to be "grounded"

[sszabo]

Thanks I’ll do some research and get back to you.