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2.2 Audio conference bridge  (Page 3/7)

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The callback function template

void process(Int16 *r_data, Int16 *w_data {/* Processing functions (user-defined) */ }

Using the driver in the ccs environment

In this section we will describe the way the driver is used in the CCS environment.

  1. Create a new project in the CCS environment
  2. Copy the following files to the project directory This is not mandatory. You may add the files from any directory. :
  • aic24.c
  • aic24.h
  • aic24_defs.h
  • AIC24-C6713.cdb
  • Add aic24.c and AIC24-C6713.cdb files to your project.
  • Add the user file with the callback function.

An example of this process is provided in the next section.

An example

The example creates two audio paths as follows:

Path # 1: J14 ⇒ CODEC#0/INP1 ⇒ SMARTDM/Channel 0 ⇒ McBSP1/Channel 0 ⇒ DSP ⇒ McBSP1/Channel 2 ⇒ SMARTDM/Channel 2 ⇒ CODEC#2/OUTP1 ⇒ J4

Path # 2: J13 ⇒ CODEC#2/INP3 ⇒ SMARTDM/Channel 2 ⇒ McBSP1/Channel 2 ⇒ DSP ⇒ McBSP1/Channel 0 ⇒ SMARTDM/Channel 0 ⇒ CODEC#0/OUTP2 ⇒ J5

The example is illustrated in Figure 9. A user defined function “test.c” was created for this application.

CCS Example Configuration

The program

The first part of the program defines the buffers for reading and writing samples.

Buffer allocation

#define NUM_CODECS 4 // The number of CODECs connected #define DATANUM 128 // The number of samples in each channel#define DATAMODE 0 // AIC24 operates in data mode #if 〔DATAMODE == 1〕#define BUFS_PER_CHANNEL 1 #else#define BUFS_PER_CHANNEL 2 #endifInt16 r_data1[DATANUM*NUM_CODECS*BUFS_PER_CHANNEL]; // data buffer for readInt16 w_data1[DATANUM*NUM_CODECS*BUFS_PER_CHANNEL]; // data buffer for readInt16 r_data2[DATANUM*NUM_CODECS*BUFS_PER_CHANNEL]; // data buffer for writeInt16 w_data2[DATANUM*NUM_CODECS*BUFS_PER_CHANNEL]; // data buffer for write

The callback function follows the template introduced in the previous section, and calls the subroutine “copyData”.

The callback function

void copyData〔Int16 *inbuf, Int16 *outbuf, Int16 length〕 {Int16 i = 0;for 〔i = 0; i<length; i++rbbrk; { outbuf[i]= inbuf[i];} }// The callback function that is called when the EDMA buffers are full // The function copies the data from channel 0 to channel 2void process(Int16 *r_data, Int16 *w_data) {if (hAIC24.DataMode) {int i; for (i=0; i<DATANUM; i++) r_data[0*DATANUM+i]⩓= 0xfffe; }copyData(r_data+0*DATANUM, w_data+2*DATANUM, DATANUM); }

The main program:

  • Sets the AIC24 handle
  • Maps the analog ports The driver sets a default configuration. Those commands are needed if changes in the default configuration are required.
  • Starts the AIC24

After this step, the program will enter in an endless loop. Samples will be processed each time an EDMA interrupt occurs.

The “main” program

int main() {// setting up the AIC24 handle AIC24_InitDefaults(⩓hAIC24, NUM_CODECS, DATANUM, r_data1, r_data2, w_data1, w_data2, process);// determining data mode (continuous or programming) hAIC24.DataMode = DATAMODE;// example for setting devices input and outputs // if defaults are ok then this is not necessaryhAIC24.Regs[0].creg6.reg6a.control_bit.mici = 0;hAIC24.Regs[0].creg6.reg6a.control_bit.inp1 = 1;hAIC24.Regs[0].creg6.reg6a.control_bit.inp2 = 0;hAIC24.Regs[0].creg6.reg6a.control_bit.inp3 = 0;hAIC24.Regs[0].creg6.reg6a.control_bit.inp4 = 0;hAIC24.Regs[0].creg6.reg6b.control_bit.outp1 = 0;hAIC24.Regs[0].creg6.reg6b.control_bit.outp2 = 1;hAIC24.Regs[0].creg6.reg6b.control_bit.outp3 = 0;hAIC24.Regs[1].creg6.reg6a.control_bit.mici = 0;hAIC24.Regs[1].creg6.reg6a.control_bit.inp1 = 0;hAIC24.Regs[1].creg6.reg6a.control_bit.inp2 = 0;hAIC24.Regs[1].creg6.reg6a.control_bit.inp3 = 0;hAIC24.Regs[1].creg6.reg6a.control_bit.inp4 = 0;hAIC24.Regs[1].creg6.reg6b.control_bit.outp1 = 0;hAIC24.Regs[1].creg6.reg6b.control_bit.outp2 = 0;hAIC24.Regs[1].creg6.reg6b.control_bit.outp3 = 0;hAIC24.Regs[2].creg6.reg6a.control_bit.mici = 0;hAIC24.Regs[2].creg6.reg6a.control_bit.inp1 = 0;hAIC24.Regs[2].creg6.reg6a.control_bit.inp2 = 0;hAIC24.Regs[2].creg6.reg6a.control_bit.inp3 = 1;hAIC24.Regs[2].creg6.reg6a.control_bit.inp4 = 0;hAIC24.Regs[2].creg6.reg6b.control_bit.outp1 = 1;hAIC24.Regs[2].creg6.reg6b.control_bit.outp2 = 0;hAIC24.Regs[2].creg6.reg6b.control_bit.outp3 = 0;hAIC24.Regs[3].creg6.reg6a.control_bit.mici = 0;hAIC24.Regs[3].creg6.reg6a.control_bit.inp1 = 0;hAIC24.Regs[3].creg6.reg6a.control_bit.inp2 = 0;hAIC24.Regs[3].creg6.reg6a.control_bit.inp3 = 0;hAIC24.Regs[3].creg6.reg6a.control_bit.inp4 = 0;hAIC24.Regs[3].creg6.reg6b.control_bit.outp1 = 0;hAIC24.Regs[3].creg6.reg6b.control_bit.outp2 = 0;hAIC24.Regs[3].creg6.reg6b.control_bit.outp3 = 0;// Starting the AIC24 AIC24_Start(⩓hAIC24);

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Source:  OpenStax, From matlab and simulink to real-time with ti dsp's. OpenStax CNX. Jun 08, 2009 Download for free at http://cnx.org/content/col10713/1.1
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