As a beginning disclaimer, I don't know a whole lot about C++ programming, so I'm trying to learn. I've done some Java, and Python, and embedded C, but mostly simple projects.
I'm planning out a library that would use the I2C bus to communicate with an IMU unit I'm using. I have the I2C interface working in my main code, but a library would make interfacing a little more organized and easier to deal with.
One of the devices on the IMU board is an ITG3200 gyro, so I took a look at the ITG3200 library for a starting point (I don't know anything about writing libraries). I see that in ITG3200.cpp that the constructor looks like this:
ITG3200::ITG3200(PinName sda, PinName scl) : i2c_(sda, scl) {}
Afterwards, the object "i2c_" is used to access the I2C bus. My confusion arises from the fact that nowhere in the code is the i2c_ object created (instantiated?) like you would in a normal program (shown below), as I would expect.
I've looked everywhere I possibly could to see if there was a general instantiation of the i2c_ object (throughout the .cpp file from above, the .h file for the library, and in the mbed.h library code as well).
Can anyone explain how this process works? I could just modify the code and create my own library using a similar constructor, but I think its important to understand how this all works. Also, could anyone explain the syntax that constructor (or others like it)?
Thanks in advance,
Dan
Daniel Kouba.
1 reply
As a beginning disclaimer, I don't know a whole lot about C++ programming, so I'm trying to learn. I've done some Java, and Python, and embedded C, but mostly simple projects.
I'm planning out a library that would use the I2C bus to communicate with an IMU unit I'm using. I have the I2C interface working in my main code, but a library would make interfacing a little more organized and easier to deal with.
One of the devices on the IMU board is an ITG3200 gyro, so I took a look at the ITG3200 library for a starting point (I don't know anything about writing libraries). I see that in ITG3200.cpp that the constructor looks like this:
ITG3200::ITG3200(PinName sda, PinName scl) : i2c_(sda, scl) {}Afterwards, the object "i2c_" is used to access the I2C bus. My confusion arises from the fact that nowhere in the code is the i2c_ object created (instantiated?) like you would in a normal program (shown below), as I would expect.
I've looked everywhere I possibly could to see if there was a general instantiation of the i2c_ object (throughout the .cpp file from above, the .h file for the library, and in the mbed.h library code as well).
Can anyone explain how this process works? I could just modify the code and create my own library using a similar constructor, but I think its important to understand how this all works. Also, could anyone explain the syntax that constructor (or others like it)?
Thanks in advance,
Dan