omap-l137\tms320c6747 signal in and out

Which example are you running that is not working? Which part of the example is not working properly?

Jeff

Hello,

As I have explained, I am trying to connect a probe to the line in port and want to see the signal from the line out port in  the oscilloscope, I just want to know how to do that .....

is there any program or code that we have to run to get the signal from line out port when the input is given at line in using a function generator?, If so I would like to know how to do that, consider this as important.

Yes check out the AIC3106 test that comes with the OMAP-L137 EVM board support package. It has an audio loopback example which should do what you need.

Jeff

Hello,

Thanks for the audio loop back example, I tried that , yet I was unable to find out the audio example as given in Ti 's wiki website, below is the path which was in the website

C:\Program Files\Texas Instruments\pspdrivers_01_20_00\packages\ti\pspiom\examples\evm6747\audio\build

I have pspdrivers_01_20_03 instead of the above is this the reason?

My second question is I want to write a basic program to process some signal which I take from line in and send to line out , do i have to change the codec test which you have shown to me? or if not How should I write a simple basic program where I want to do processing on the signal from line and send to line out . I have not written any program as now, and there are no books for evm 6747 all the books are about dks6713 and all, can you help me ...because which files have to be included in the project and what is the purpose and all are very confusing and I am not able to work with them....

My main objective is to modulate the signal from line in and then send to line out using BPSK modulation and i need help how to do that  ?

Regards

Akshay Malhotra 

Look in aic3106_loop_linein.c at the following lines:

                /* Read then write the left sample */
                while ( ! ( MCASP1_SRCTL0 & 0x20 ) );
                    sample_data = MCASP1_RBUF0_32BIT;
                while ( ! ( MCASP1_SRCTL5 & 0x10 ) );
                    MCASP1_XBUF5_32BIT =  sample_data;

                /* Read then write the left sample */
                while ( ! ( MCASP1_SRCTL0 & 0x20 ) );
                    sample_data = MCASP1_RBUF0_32BIT;
                while ( ! ( MCASP1_SRCTL5 & 0x10 ) );
                    MCASP1_XBUF5_32BIT = sample_data;

Once you read in the sample_data, you can create a function to perform any filtering or modulation on that data that you want. It can then be sent to the output just as the next line of the code shows.

You should be able to take the concepts from the books you have seen and apply them to this chip.

If you have any specific questions on the hardware, feel free to post them here.

Jeff

Thanks jeff your information was very usefull. I need some help again. I understood how to read the input data but I want to know how to access the interupt routine. I want to implement the following code which was for 6713 in this board ;

1 include "dsk6713_aic23.h" //support file for codec, DSK
2 Uint32 fs=DSK6713_AIC23_FREQ_96KHZ; //set sampling rate
3 #include <math.h> //for performing modulation operation
4 int i_BPSK_M, j_BPSK_M;
5 int masked_value, output;
6 //Data table for BPSK MOD
7 int data_BPSK[2][4]={0, 1000, 0, -1000,
0, -1000, 0, 1000};
8 interrupt void c_int11() //interrupt service routine
9 {
10 if (i_BPSK_M==64) //determines when to get new input
11 {
12 sample_data = input_sample(); //inputs data
13 i_BPSK_M=0;
14 j_BPSK_M=0;
15 }
16 masked_value = sample_data & 0x0001; //masks input sample as 1-bit segments
17 output = data_BPSK[masked_value][j_BPSK_M]; //gets corresponding level from table
18 output_sample(output*10); //outputs corresponding sinusoid
19 j_BPSK_M++; //repeated output counter
20
21 if (j_BPSK_M==4) //checks if 1-bit segment was output
22 {
23 j_BPSK_M=0;
24 sample_data = sample_data >> 1; //shifts input so as to mask another part
25 }
26 i_BPSK_M++;
27 return;
28 } // end of interrpt routine
29 void main()
30 {
31 i_BPSK_M=64;
32 j_BPSK_M=0;
33 comm_intr(); //init DSK, codec, McBSP
34 while(1); //infinite loop

I am not able to omplement this code , how should I use the intrupt routine for  omapl137\tms320c6747 board ?

Regards

Akshay Malhotra

Please go through all the examples in the BSL, many of which use interrupts.

Jeff

Hi jeff,

I checked the BSL , but I was not able to figure out how to use the interrupt service.I took a sine wave from the function generator and then tried to change the sample_data but was not able to understand, how to change the frequency or the gain of the signal .

secondly, could you help me to implement the above BPSK on this board , I am taking the input from a function generator as a sine wave, and would like to apply BPSK to that and see the output from the line out in the oscilloscope. This is my goal , can you help me with that.

Regards

Akshay Malhotra

Hi Jeff,

I tried to work with the code given below

 /* Read then write the left sample */
                while ( ! ( MCASP1_SRCTL0 & 0x20 ) );
                    sample_data = MCASP1_RBUF0_32BIT;
                while ( ! ( MCASP1_SRCTL5 & 0x10 ) );
                    MCASP1_XBUF5_32BIT =  sample_data;

                /* Read then write the left sample */
                while ( ! ( MCASP1_SRCTL0 & 0x20 ) );
                    sample_data = MCASP1_RBUF0_32BIT;
                while ( ! ( MCASP1_SRCTL5 & 0x10 ) );
                    MCASP1_XBUF5_32BIT = sample_data;

I tried to write several loops and change the sample data , but have know idea what is happening, if I multipkly the sample_data with 2 i get distortion , if I modify anything I get  distortion.

I need to know what kind of data is sample_data so that I can work with it.

I need yo know what is MCASP1_RBUF0_32BIT and MCASP1_XBUF5_32BIT .

I need to know what  does while ( ! ( MCASP1_SRCTL0 & 0x20 )  do ?

I would be awaiting for a reply from you as this is important .

Regards

Akshay Malhotra