Real-Time Workshop

Creating a Customized Asynchronous Library

You can use the Real-Time Workshop VxWorks asynchronous blocks as templates that provide a starting point for creating your own asynchronous blocks. Templates are provided for these blocks:

• Asynchronous Rate Transition block
• Interrupt Control block
• Unprotected Asynchronous Rate Transition block
• Task Synchronization block

You can customize each of these blocks by implementing a set of modifications to files associated with each template. These files are:

• The block's underlying S-function C MEX-file

• Note that SS_OPTION_ASYNCHRONOUS_INTERRUPT should be used when a function-call subsystem is attached to an interrupt. For further information, see documentation for SS_OPTION and SS_OPTION_ASYNCHRONOUS in matlabroot/simulink/include/simstuc.h

• The block's mask and the associated mask M-file

• Note that the strings 'read' and 'write' must appear in the mask types for rate transition blocks.

• The TLC files that control code generation of the block

At a minimum, you must rename the system calls generated by the TLC files to the correct names for the new real-time operating system (RTOS) and supply the correct arguments for each file. There is a collection of files that you must copy (and rename) from matlabroot/rtw/c/tornado/devices into a new directory, for example, matlabroot/rtw/c/my_os/devices. These files are:

• Asynchronous Rate Transition block -- vxdbuffer.tlc, vxdbuffer.c
• Interrupt Control block -- vxinterrupt.tlc, vxinterrupt.c, vxintbuild.m
• O/S include file -- vxlib.tlc
• Task Synchronization block -- vxtask.tlc, vxtask.c

Unprotected Asynchronous Rate Transition Block

Targeting Real-Time Systems