Actions
Forum Thread Details
  • Replies 1 reply
  • Subscribers 46 subscribers
  • Views 360 views
  • Users 0 members are here
Related

Issue using i2c library

electronichussar

Hey everyone. I'm trying to use the Azure Sphere to build a chess playing robot. To control the stepper motors to move the arm I am using the two click boards from the link: https://www.mikroe.com/stepper-13-click

This board uses the PCA9538A i2c expander chip. Now when I am trying to compile in Visual Studio I use the i2c library as documented by Microsoft but whenever I try to use a function that should exist in that library I receive the error "implicit declaration of function 'I2CMaster_WriteThenRead' [-Werror=implicit-function-declaration]". Does anyone have any idea of what I need to do to fix this?

  • For Azure code, I've found I have to see the entire solution to troubleshoot stuff like this, but, here is where I'd start:

     

    This message occurs when the compiler has no function declaration to refer to.  A function declaration provides the compiler the functions return type as well as the variable types passed as parameters in the function.

     

    Function declarations are most frequently provided in ".h" files known as header files.  The header files are referenced towards the top of your code using the "preprocessor directive" named "#include".  The compiler will add that code stated in the #include directive prior to compiling and in turn have no "implicit declarations".

     

    So, to troubleshoot, look at the top of the script that the error references.  After all the comments, look for a section with a few lines like.

    #include <file.h>

     

    It may be as simple as you need add the following line in that section:

    #include "i2c.h"

     

    In my Azure code, in the i2c.c file, I have a section of preprocessor directives that have two header files for i2C:

    #include <applibs/i2c.h>
....
#include "i2c.h"

     

    A quick Google reference for more info:  https://www.tutorialspoint.com/cprogramming/c_header_files.htm

     

    For my Azure code, I used the Avnet Azure Sphere example as my starting base.  I put code for my additional I2C devices in the i2c.c code to quickly get things going.  Otherwise, I would have had to do a let of sorting like above and find a way to trigger my sensor calls.  In particular, I added the sensor calls to the AccelTimerEventHandler() function so it would get my devices I2C sensor data when it got the sensor data from the Azure Sphere.

     

    See ya',

    Sean