# voxl-io & I2C

Source: https://forum.modalai.com/topic/55/voxl-io-i2c
Category: Flight Core and Legacy VOXL (https://forum.modalai.com/category/9/flight-core-and-legacy-voxl)
Tags: voxl-flight
Posted: 2020-12-08 16:03:23 UTC by traffic_light
Replies: 4 · Views: 1298

## traffic_light · 2020-12-08 16:03:23 UTC

Hello everyone,

Currently I'm developing some software that will talk, over I2C, to a self-build powermodule with a microcontroller onboard.
This software is a node for ros and runs in a docker.
When it received the batterypercentage from PX4 it will start sending and receiving data to the powermodule.
The part that receives the batterypercentage works great.

The only problem is that I receive a linker error when I'm building the software with the I2C commands

Error's:
```
CMakeFiles/powermodule_node.dir/src/powermodule.cpp.o: In function `PowerModule::OpenI2CDevice()':
powermodule.cpp:(.text+0xbc): undefined reference to `voxl_i2c_slave_config'
powermodule.cpp:(.text+0xd0): undefined reference to `voxl_i2c_init'
collect2: error: ld returned 1 exit status
powermodule/CMakeFiles/powermodule_node.dir/build.make:165: recipe for target '/root/yoctohome/peter-dev/control/devel/lib/powermodule/powermodule_node' failed
make[2]: *** [/root/yoctohome/peter-dev/control/devel/lib/powermodule/powermodule_node] Error 1
CMakeFiles/Makefile2:1551: recipe for target 'powermodule/CMakeFiles/powermodule_node.dir/all' failed
make[1]: *** [powermodule/CMakeFiles/powermodule_node.dir/all] Error 2
Makefile:138: recipe for target 'all' failed
make: *** [all] Error 2
Invoking "make -j4 -l4" failed

```

I already tried a lot of option.
Some options i already did:
* Include a lot of header and cpp files into the includes folder
* Building the voxl_io in a docker on my pc and move the ipk to the voxl

The hardware is a voxl_flight and I'm using the I2C port 6 (located on the J7 header)

I don't know what to do for now so I'm searching for help. I can't find anything that helps me with my solution and the docs of modalai doesn't have a lot of information about I2C usage.

Here a part of the code that's opening the i2c:
```
int8_t PowerModule::OpenI2CDevice()
{
    if (I2C_is_open_)
    {
        // I2C bus is already opened. Return -2
        return -2;
    }

    if (voxl_i2c_slave_config(I2C_bus_id_, I2C_address_, 400000, 1000) == 0)
    {
        //return -3;
    }

    int8_t response{0};
    response = voxl_i2c_init(I2C_bus_id_);

    if (response == 0)
    {
        I2C_is_open_ = true;
    }

    return response;
}
```

Thanks in advance!

(I'm sorry for my English ;-) )

## Reply by modaltb (ModalAI staff) · 2020-12-08 16:31:26 UTC

Hi @traffic_light ,

Are you building your application in the voxl-docker or on target (e.g. on VOXL)?

Is it possible to post your CMakeLists.txt file here?  It looks like it's failing to link to libvoxl_io. 

Here's an example file where we build some applications, one of which is an i2c tester, which may help:

https://gitlab.com/voxl-public/core-libs/libvoxl_io/-/blob/master/lib/apps/CMakeLists.txt#L51

(also, your English is Great!)

Thanks!

## Reply by traffic_light · 2020-12-08 19:36:51 UTC

Hello @modaltb ,

Thank you for your (really fast) answer!

I'm building it with catkin_make inside the docker image.
Maybe I need to mount more files into the docker image?
Currently I added some header and cpp files to the include folder inside the project.

I'm currently not at work, it's 20:40 over here, so I can't send the makefile.
I'll tryout your suggestion the first thing tomorrow.

By the way: I'm sorry for posting it, atleast that's what it think, in the wrong forum part. Developing software forum was a better option ;-)

## Reply by traffic_light · 2020-12-08 21:46:45 UTC (in reply to traffic_light)

@traffic_light (So, the makefile is a catkin makefile. A little bit different then a normal cmakelist files)

## Reply by traffic_light · 2020-12-09 13:03:15 UTC (in reply to modaltb)

@modaltb my current cmake without the addition you mentioned:
```
cmake_minimum_required(VERSION 2.8.3)
project(powermodule)

## Compile as C++11, supported in ROS Kinetic and newer
add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTS
  roscpp
  std_msgs
)

## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)

## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
################################################

## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder
# add_message_files(
#   FILES
#   Message1.msg
#   Message2.msg
# )

## Generate services in the 'srv' folder
# add_service_files(
#   FILES
#   Service1.srv
#   Service2.srv
# )

## Generate actions in the 'action' folder
# add_action_files(
#   FILES
#   Action1.action
#   Action2.action
# )

## Generate added messages and services with any dependencies listed here
# generate_messages(
#   DEPENDENCIES
#   std_msgs
# )

################################################
## Declare ROS dynamic reconfigure parameters ##
################################################

## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )

###################################
## catkin specific configuration ##
###################################
## The catkin_package macro generates cmake config files for your package
## Declare things to be passed to dependent projects
## INCLUDE_DIRS: uncomment this if your package contains header files
## LIBRARIES: libraries you create in this project that dependent projects also need
## CATKIN_DEPENDS: catkin_packages dependent projects also need
## DEPENDS: system dependencies of this project that dependent projects also need
catkin_package(
  #INCLUDE_DIRS ../../include
  #LIBRARIES powermdole
  #CATKIN_DEPENDS roscpp std_msgs
  #DEPENDS system_lib
)

###########
## Build ##
###########
# DOESN'T WORK:
#FASTRPC_STUB_GEN(../../include/io_rpc.idl)

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
	${catkin_INCLUDE_DIRS}
	include
	./include
	/usr/local/include
	/usr/include
	../../include/
)

link_directories(
	../../include
	/include
	include
	/usr/local/lib
	/usr/lib
)

## Declare a C++ library
add_library(${PROJECT_NAME}
   src/${PROJECT_NAME}.cpp
)

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
#add_executable (voxl_i2c  ../../include/voxl-i2c.c)
#target_link_libraries (voxl_i2c  /usr/lib/voxl_io)

add_executable(${PROJECT_NAME}_node 
   src/main.cpp
   src/powermodule.cpp
   ../../include/colorprinting.cpp
)

## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
#add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
target_link_libraries(${PROJECT_NAME}_node
${catkin_LIBRARIES}
/usr/local/lib/
# /usr/lib/aarch64-linux-gnu/libi2c.so
#/usr/lib/rfsa/adsp/libio_rpc.so
#/usr/lib/rfsa/adsp/libio_rpc_skel.so
#/usr/lib/libvoxl_io.so
#/usr/lib/libvoxl_io
)

#############
## Install ##
#############

# all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# install(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )

## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )

## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )

#############
## Testing ##
#############

## Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_shutdown.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()

## Add folders to be run by python nosetests
# catkin_add_nosetests(test)
```

I think I need to figure out how I can add the IO correctly inside it.
I'll post a new makefile when I did that.