Differences

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--- for_developers:wrapper_lib [2017/04/17 19:46] – graf
+++ for_developers:wrapper_lib [2017/04/18 12:43] (current) – kalberer
@@ Line 1: / Line 1: @@
 ====== Create new Wrapper Library ======
-The following steps have to be taken in order to create a custom wrapper library.
+The following steps have to be taken in order to create a custom wrapper library. See also [[https://github.com/eeros-project/flink-eeros|flink-eeros]] or [[https://github.com/eeros-project/comedi-eeros|comedi-eeros]].
-  - Create new CMake project for a shared library.
-  - Include and link against necessary hardware library.
+  - Create new CMake project for a shared library.
-  -
+  - Include and link against EEROS: <code>find_package(EEROS REQUIRED)
+include_directories(${EEROS_INCLUDE_DIR})
+link_directories(${EEROS_LIB_DIR})</code>
+  - Include and link against necessary hardware library. If the required hardware library generates a CMake Package, use ''find_package()'' to search for the library: <code>find_package(flink REQUIRED)
+include_directories(${FLINK_INCLUDE_DIR})
+link_directories(${FLINK_LIB_DIR})</code> If you have no CMake Package you have to search for an installed header file or add it as additional include and library directory. <code>find_path(COMEDI_INCLUDE_DIR NAMES comedi.h comedilib.h)
+if(COMEDI_INCLUDE_DIR)
+        include_directories(${COMEDI_INCLUDE_DIR})
+endif()
+find_library(COMEDI_LIBRARY comedi)
+if(COMEDI_LIBRARY)
+	message(STATUS "-> libcomedi available")
+	set(COMEDI_LIBRARY_DIR ${COMEDI_LIBRARY_DIR} comedi)
+endif()</code>
+  - Create classes for every type you intend to support (AnalogOut, DigitalIn, PWM, ...):
+    - These classes have to derive from the EEROS HAL classes In- or Output respectively ScalableIn- or ScalableOutput. You can find these classes in the EEROS repository in folder ''/includes/eeros/hal''. This allows you to access the member functions of the derived classes when they are loaded dynamically over the configuration file.
+    - Implement the derived functions for every class. The ''set()'' and ''get()'' functions have to access the hardware library and write or read from hardware according to their functionality.
+    - For scalable channels ''scale'' and ''offset'' (member variables of ScalableIn- and ScalableOutput) have to be taken into account. Calculate the effective output value set to the hardware with these values. Check AnalogOut of [[https://github.com/eeros-project/comedi-eeros|comedi-eeros]] for an example. Scale and offset describe the scaling factors of the connected hardware. So you have to divide the output value by scale.
+    - Create a C function ''createType'', which will be called dynamically from EEROS for every supported type. This function has to create an object of the corresponding type and returns a pointer to it.
+    - Create all necessary Feature Functions as C functions. These are intended to use for all actions which cannot be called with the derived functions like setting a PWM frequency.
+  - Create a class to handle the hardware device node (''open'', ''close'', ...). Create a factory for the device. On every creation of a channel there will be an access to ''getDevice()'' and you have to make sure that the device is opened only once.