AN2113 Freescale Semiconductor / Motorola, AN2113 Datasheet - Page 23

• Manufacturer Part Number: AN2113
• Description: AN2113 Multichannel Voice Coding System on the RTXC Operating System
• Manufacturer: Freescale Semiconductor / Motorola

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1. Signal semaphore
The integration of the command line interface task cli_drv with the SCI character I/O mechanisms
described in Section 7.4 is shown in Figure 18. The CLI driver task
character command is detected in the SCI input driver task (sci_idrv). The cli_drv task then
accesses the CHANNEL_CONFIGURATION C structure to display or change a channel’s state information.
Messages are sent to the user from the CLI task by enqueueing characters in the RTXC output queue.
Additionally, a task that echoes characters (sci_echo) typed by the user is signaled when a character is
placed in the RTXC input queue.
We used the Tasking make utility (mk563.exe) to build the application. Integration at this level involved
proper compilation and linking of the RTXC library, the IS-96-A voice coder library, and the application
object files and other the system configuration files.
As communications systems continue to increase in complexity, equipment manufacturers rely more and
more upon third parties to develop standard software for a chosen DSP architecture, high-level languages
to easily port code between systems, and RTOSs to integrate various system tasks to guarantee task
handling. Remember that using an RTOS has the following trade-offs:
Motorola is committed to continued support of RTOS usage and other innovations in DSP technology that
can be used to decrease the development time required of equipment manufacturers.
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Conclusions
It adds overhead, but this can be kept to a minimum by choosing a well-designed RTOS such as
RTXC and designing a system efficiently.
It is not difficult to use. A different way of looking at things is necessary, but the main step in
converting existing code to use an RTOS is to divide the program into tasks that usually flow with
the function organization. A robust RTOS is absolutely necessary.
It can be used in real-time DSP applications.
It is a part of the trend towards software portability.
sci_idrv
Task
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cli_drv
Queue
Input
Figure 18. Command Line Interface Task
Task
Multichannel Voice Coding System
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2. Access channel
sci_echo
Task
information
Queue
Output
Channel_Configuration
cli_drv
3. Send message
Structure
is signaled if a valid
sci_odrv
Task
Conclusions
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