Standalone Arduino Altimeter

Here is a standalone altimeter working with Arduino that you can use in RC project, hiking, cars... where you want :)

It shows on first screen the altittude, the temperature & the air pressure, and in the second, the minimum / maximum altitude reached.

Parts needed: (~12$)

• An arduino board like a nano, pro mini or even AtTiny85 (depends on what you want, pro mini is lighter than nano and can works with an input voltage of 3.3v to 12v, perfect for light weight RC) 3.29$ on ebay
  
• BMP280 chip temperature & barometric pressure sensor 1.84$ on ebay
• An OLED display (0.96" I2C IIC Série 128X64) 5.32$ on ebay
• Iron solder, tin and wires
• A plastic case to put all in 1.50$ on ebay

Step 1: The Wiring

The wiring is simple, the most "complicated" is to find the SCL and SDA pin on your arduino.

On the nano as on the photo, pin A4 is SDA and pin A5 is SCL.

On the Pro Mini, take a look at the picture, SDA is upside right to pin A2, and SCL upside right to pin A3.

Once your wiring is done, lets upload the sketch to the Arduino !

Step 2: The Program

Code explanations (full code below):

#include "U8glib.h"
#include "BMP280.h"

They are the 2 libraries you have to put inside Documents\Arduino\libraries\

#define P0 1021.97

This is where you calibrate the altimeter, changing this value. Once it's done, it's pretty accurate !

(by default it was 1013.25, i had to up it to 1021.97 to have the right altitude in my town)

U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NO_ACK);

Here you define the Oled screen type (128x64 etc...)

  u8g.drawStr( 5, 10, "Temp: ");
  u8g.drawStr( 5, 30, "Bar : ");
  u8g.drawStr( 5, 50, "Alt : ");
  u8g.drawStr( 50, 10, sT);
  u8g.drawStr( 50, 30, sP);
  u8g.drawStr( 50, 50, sA);

Here the informations you want to display on first screen and their position ( Y, X, VALUE)

  dtostrf(A_MIN, 4, 2, sA_MIN);
  dtostrf(A_MAX, 4, 2, sA_MAX);
  u8g.drawStr( 5, 20, "A Min: ");
  u8g.drawStr( 60, 20, sA_MIN);
  u8g.drawStr( 5, 45, "A Max: ");
  u8g.drawStr( 60, 45, sA_MAX);

Same for second screen

      if ( A > A_MAX) {
        A_MAX = A;
      }

      if ( A < A_MIN || A_MIN == 0) {
        A_MIN = A;
      }

Here we update the minimum and maximun altitude stored

      do {
        draw(T, P, A);
      } while ( u8g.nextPage() );
      u8g.firstPage();
      delay(1000);

Here, with the delay value (1000 in this case), you will stay 1 second on the first screen before switching to the second one. So change that if you want to customize display time :)

      do {
        draw2(A_MIN, A_MAX);
      } while ( u8g.nextPage() );
      u8g.firstPage();
      delay(1000);

Same for second screen !

Hope it's clear, feel free to post a question in comments if needed !

Here is the full code:

#include "U8glib.h"
#include "BMP280.h"
#include "Wire.h"
#define P0 1021.97  //1013.25 
BMP280 bmp;

// OLED Type
U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NO_ACK);

char sT[20];
char sP[9];
char sA[9];
char sA_MIN[9];
char sA_MAX[9];
double A_MIN = 0;
double A_MAX = 0;

void draw(double T, double P, double A) {
  u8g.setFont(u8g_font_unifont);

  dtostrf(T, 4, 2, sT);
  dtostrf(P, 4, 2, sP);
  dtostrf(A, 4, 2, sA);

  u8g.drawStr( 5, 10, "Temp: ");
  u8g.drawStr( 5, 30, "Bar : ");
  u8g.drawStr( 5, 50, "Alt : ");
  u8g.drawStr( 50, 10, sT);
  u8g.drawStr( 50, 30, sP);
  u8g.drawStr( 50, 50, sA);
}

void draw2(double A_MIN, double A_MAX) {
  u8g.setFont(u8g_font_unifont);

  dtostrf(A_MIN, 4, 2, sA_MIN);
  dtostrf(A_MAX, 4, 2, sA_MAX);
  u8g.drawStr( 5, 20, "A Min: ");
  u8g.drawStr( 60, 20, sA_MIN);
  u8g.drawStr( 5, 45, "A Max: ");
  u8g.drawStr( 60, 45, sA_MAX);
}

void setup() {
  Serial.begin(9600);
  if (!bmp.begin()) {
    Serial.println("BMP init failed!");
    while (1);
  }
  else Serial.println("BMP init success!");

  bmp.setOversampling(4);

  u8g.setColorIndex(1);
  u8g.setFont(u8g_font_unifont);
}

void loop(void) {
  double T, P;
  char result = bmp.startMeasurment();

  if (result != 0) {
    delay(result);
    result = bmp.getTemperatureAndPressure(T, P);

    if (result != 0) {
      double A = bmp.altitude(P, P0);

      if ( A > A_MAX) {
        A_MAX = A;
      }

      if ( A < A_MIN || A_MIN == 0) {
        A_MIN = A;
      }

      //      Serial.print("T = \t"); Serial.print(T, 2); Serial.print(" degC\t");
      //      Serial.print("P = \t"); Serial.print(P, 2); Serial.print(" mBar\t");
      //      Serial.print("A = \t"); Serial.print(A, 2); Serial.println(" m");

      u8g.firstPage();
      do {
        draw(T, P, A);
      } while ( u8g.nextPage() );
      u8g.firstPage();
      delay(1000);

      do {
        draw2(A_MIN, A_MAX);
      } while ( u8g.nextPage() );
      u8g.firstPage();
      delay(1000);
      
    }
    else {
      Serial.println("Error.");
    }
  }
  else {
    Serial.println("Error.");
  }

  delay(100);

}

Step 3: Now It's Up to You !

You can move form the breadboard to the plastic case with soldering all.

Then, put it on RC plane, RC quadcopter, RC helicopter..... or a water rocket !

Hope it was helpful and that you will send me a pic once it's done =)

Comments

[samern]

I happen to have a BMP 180 lying around here. It seems like the only difference is the SDO pin. Any reason not to use that and ignore that connection (keeping everything else the same)? Would be nice to put it to use for this.

[Tailspin9]

If i want to display the Alt in feet instead of Meters - How do i change that Formula - or where.
Thanks For a nice project.

[Shoyun]

Hi !

1m = 3,28084 ft

So replace

double A = bmp.altitude(P, P0);

by

double A = bmp.altitude(P, P0) * 3,28084;

[TrevorS17]

Followed all instructions on this page and it doesn't compile. Has error's.

[Gangesh Tomar]

How do I power it
Which pin
Which battery

[Gangesh Tomar]

I did not understand wiring in ardunio pro mini
Please explain

[Gangesh Tomar]

There is no button
How will we change to the next screen
How will the 1 second delay work

[Gangesh Tomar]

Hi
You have solved my great problem
I don't know how much should I thank you
Basically I wanted a altimeter for model rockets
Altimeters available are very costly and the One you made is very cheap
Only one problem that I'M new to ardunio
I will copy the code but I did not understand code line 1 and 2
How we will insert library ?
Please tell me.
Thank you very much

[djessie.bolks]

Hey Shoyun,

I was wondering if the altitude is in meters or feet or something else.

Thanks

Djessie

[Shoyun]

Hi Djessie, for what i remember it was meters :)

[djessie.bolks]

Thanks

[djessie.bolks]

Hey,

For a school project i'm making a rocket and I really want to know how high it'll get. So I want to make this altimeter and attach it to my rocket. But if I do that how can I power the arduino?

I hope you'll still read this.

Djessie

[djessie.bolks]

Okay I just found out that you can just power it with a 9 volt battery by, directly connecting the battery positive to the VIN pin and the battery negative to the GROUND pin

[Shoyun]

Hi Djessie ! Depending of the arduino model that ur using, there are a voltage range which you can use to power it up. If a 9v battery fits, perfect, or you could use a lightest lipo (with a voltage booster if needed) if you want to gain some grams. Wish you a good and enjoyable school project :)

[djessie.bolks]

Thank you that helps a lot

[djessie.bolks]

By the way I am using a nano arduino

[steveflora]

Question about the barometric pressure.

I'm assuming the 1013.25 is the nominal pressure at sea level. I live at 2800 feet. Is there a table or something you reference to get the nominal pressure for where I live?

Also

I'm interested in the feed back you go how the whole thing was mounted. My plan is to make a couple of these to mount in my land cruiser and 73 chevy pickup. I'm looking for what is available off the shelf that could mount nicely in both vehicles

Steve Flora
Middleton, Idaho (USA)

[arooster1]

the local pressure readings will change over time due to weather fluxuaitons (high pressure systems, low pressure systems, etc.). You can get updated settings for your area from weather reports or search for the local airport's "METAR" (it's a condensed weather report for pilots). All aircraft set their alitimeters using the local pressure reading for the airport that they're taking off from or landing at.

[Wookie01]

Hi, I am really keen to complete this project but I am very new to Arduino and C++.

No doubt this is something that experienced coders see every day, and I am sorry if it is frustrating that newbies don't understand it. :(
I have researched for days trying to solve this without reaching out, but it has defeated me.

I have downloaded the .ino file and libraries, and imported the libraries into my Arduino system.

When I try to compile the sketch I get the following error messages and I cannot determine where or why they are being generated?

In function 'void setup()':
standalone_altimeter.ino:56:7: error: 'class BMP280' has no member named 'setOversampling'
bmp.setOversampling(4);

In function 'void loop()':
standalone_altimeter.ino:65:21: error: 'class BMP280' has no member named 'startMeasurment'
char result = bmp.startMeasurment();

In the loop section I also have similar errors for
'getTemperatureAndPressure' and
'altitude'

If anyone is able to advise how to fix these errors I would be extremely grateful.

Thanks,
Graham

[Wookie01]

I have solved this, the problem was that the system was not loading the libraries supplied above, but was drawing them from the arduino stock library.

I was able to force the correct libraries and now it is completing verification.

Next step is to source an I2C OLED to complete the hardware setup, then it should be up and running hopefully