C++ library for BMP085 barometer for I2C communication with Arduino Wire library. Main features:
- read raw data
- calculate scaled data
- registers setting
- waiting for readout without delay (the conversion time is 25.5ms at maximum)
- moving average filtering (for pressure and temperature)
The library is intended to work without any user interference, just open project and upload working example and use it.
Library uses I2C Interface, I2C Sensor Interface to simplify and unify working with I2C devices. The library also uses Status Class which is optional.
The working example for this library is written in Atmel Studio 7 with Visual Micro addon. But it is possible to run it with Arduino IDE by adding files to project (probably there will be need to change the #include paths).
- Software:
- Atmel Studio 7 (tested) or Visual Studio,
- Visual Micro addon for above AS7 or VS.
- Hardware:
- Arduino Due (tested) or Arduino Uno (any ATmega 328P) board,
- BMP085 board or any IMU sensor with BMP085.
| BMP085 board | Due board | Uno board |
|---|---|---|
| SCL | SCL (21) | SCL (A4) |
| SDA | SDA (20) | SDA (A5) |
| VCC 3.3V | 3.3V | 3.3V |
| VCC 5V | - * | 5V |
| GND | GND | GND |
*The Due MCU cannot be exposed to the voltage above 3.3V level!
To see a real-life example open AS7 project file BMP085_.atsln and upload the BMP085_.ino to a micro-controller. You should see something like that on Serial Monitor (baud rate = 115200):
2 Serial initialized with baudrate = 115200
6 Found BMP085 searching device with ID = 0x77
10 Pressure 0 Altitude 44330.00 Temperature 0.00
20 Pressure 0 Altitude 44330.00 Temperature 25.80
...
1260 Pressure 99237 Altitude 175.30 Temperature 25.80
1271 Pressure 99237 Altitude 175.30 Temperature 25.80
...
To change above in BMP085_.ino file uncomment and choose appropriate in below:
// Set Mode or use defaults from BMP085::init()
// Barometer.setMode(->your_setting<-);
By default in the library is working moving average over pressure data in order to get better results. You can disable it by changing in BMP085.h file the ENABLE_MOVING_AVERAGE_FILTERING define to 0x00:
#define ENABLE_MOVING_AVERAGE_FILTERING 0x00Also, you can set the number of samples for moving average by changing in BMP085.h file the BMP085_MOVING_AVERAGE_RANGE define to appropriate, by default:
#define BMP085_MOVING_AVERAGE_RANGE 20Important: The pressure and altitude values are valid after
2 * BMP085_MOVING_AVERAGE_RANGE * conversion time depending on Mode settings
milliseconds, by default: mode = ultra high resolution and BMP085_MOVING_AVERAGE_RANGE = 20 it is after ~1000 ms.
BMP085::read() method can be polling in loop, which provide the fastest way to get new data from barometer. There is a mechanism that is responsible for waiting for the barometer to be asked for new data without blocking the processor.