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11 years, 8 months ago.
how do i define and use a global instance of defined mbed class?
below is my setup. I want to use mbed i2c pre-defined class, with only a single i2c_2 object(since they use the same pins), in multiple files. but i cant get it to work. any help?
bad code
-----------------global.h------------------
extern I2C i2c_2(p28, p27);
--------------------------global.cpp------------------
I2C i2c_2(p28, p27);
------------------------main.cpp------------------
#include global.h
#include mbed.h
void main(){
i2c_2.write(....);
}
-------------------------eeprom.h------------------
#include global.h
void eeprom();
-------------------------eeprom.cpp------------------
#include eeprom.h
void eeprom(){
i2c_2.write(....);
}
-------------------------lights.h------------------
#include global.h
void lights();
------------------------lights.cpp------------------
#include lights.h
void lights(){
i2c_2.write(....);
}
------------------------
2 Answers
11 years, 8 months ago.
I think if you leave out the (p28, p27) on the external declaration in global.h it should work. What error do you get?
11 years, 8 months ago.
[solved] whoops. ended up figuring out my problem. here's the correct the notation. [solved]
passing objects through multiple functions
mbed_class myobject;
function2(mbed_class *myobject){
myobject->mymember(..);
}
function1(mbed_class *myobject){
function2(myobject);
//function2(&myobject); //i used to have that "&"
}
main(){
myobject.mymember(..);
function1(&myobject);
}
ended up not using global instance.
That is indeed the best way afaik, that said there also is not really a reason to stick to one object per pair of pins. Sure a bit less memory usage, but that is really a small difference. So if you have lets say 3 sensors on a single I2C bus it isn't a problem to give each of them a different I2C object.
posted by 28 Mar 2013