AN2113 Freescale Semiconductor / Motorola, AN2113 Datasheet - Page 22

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

Software Description
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7.6 Integration
Once the individual tasks are defined and tested, the integration simply involves properly selecting task
priorities and RTXC objects to synchronize and communicate these tasks. We integrated the ESSI data I/O
software with the double buffer and voice coder software using an input dispatch task called
and an output dispatch task called
The i_dispatch task is signaled via the SSI_RISR semaphore from the ESSI last slot ISR, indicating
that all the data for a given ESSI frame has been received. This task then reads the
CHANNEL_CONFIGURATION C structure to determine the operating mode for a given channel, and
based on this information, it determines whether to ignore the input (Off mode), copy the received data
from the receive buffer RX_buff to the transmit buffer TX_buff (Pass mode), or call double buffer
mechanism and process the input data accordingly. If the receive frame buffer is full as indicated by the
corresponding flag in the CHANNEL_CONFIGURATION C structure, an RTXC message is sent to either
the Delay mode task (passbuff) or the IS96a mode task (is96a) indicating which channel to
process.
The input dispatcher task performs the steps described for each of the four channels supported. The use of
a CHANNEL_CONFIGURATION C structure for each channel allows the current state of the channel to be
maintained independently. Thus each channel’s data stream is processed independently. The same Delay
and IS96a tasks are used for each channel: the messages sent to these tasks contain a pointer to the
CHANNEL_CONFIGURATION C structure to use and if multiple messages are sent, the RTXC queues
them. Similarly, the output dispatcher task is o_dispatch signaled by the ESSI transmit last slot ISR.
However, this task simply writes output data to the transmit buffer (TX_buff) if Delay or IS96a
modes are used for a channel. Also, the task calls the function to implement the double buffer mechanism
for the output and transmit frame buffers.
3. Read Data Input
5. Write output or double buffer
1. ESSI Last Slot Event
Double buffers
RX_buff
TX_buff
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6. Signal processing task
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i_dispatch
Last Slot ISR
Multichannel Voice Coding System
Figure 17. Input Dispatcher Task
o_dispatch
ESSI Rx
ESSI
Task
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shown in Figure 17.
4. Read channel
mode
2. Signal ESSI Rx Semaphore
passbuff
is96a
Task
Task
Channel_Configuration
Structure
i_dispatch