values in the G buffer and the are not getting through

habeeb siddique37664

Other Parts Discussed in Thread: TMS320VC5509A

HI guys,

I am trying to send some numbers from the gBuffer from one DSk to another DSK but i am not receiving the same numbers, though when i send in audio from one dsk to another can hear the audio play, but when i send in numbers the the memory does not show the numbers in it.

Int16 gBuffer[(BUFFSIZE * BUFFERSE] = {0xCC,0x0f,0xCC,0x0f,0xCC,0x0f,0xCC,0x0f,0xCC,0x0f,0xCC,0x0f,0xCC,0x0f,0xCC,0x0f,0xCC,0x0f,0xCC,0x0f,

0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55};

this is what i am sending from the gBuffer on one DSK to another and not receving the numbers on the gBuffer on the other DSK.

thanks habeeb

over 14 years ago

0 Mark M over 14 years ago

TI__Mastermind 30120 points

Hi Habeeb,

Could you provide more information?

Which DSK / DSP are you working with? Are you modifying some example code? How are you transferring the data? Through a serial port?

Thanks,
Mark

0 habeeb siddique37664 over 14 years ago in reply to Mark M

Intellectual 640 points

hi mark,

I am using the TMS320VC5509A DSK, no i am not modifying the example code dsk_app.c i am jus running the audio streaming example project

there i am putting in the hexa values in buffer and send them to see them being received on another board.

I am using the " LINE IN " and "LINE OUT " codecs I/Os for sending in the hexa values,

when I send in audio like an input of a song audio playing from the computer i can hear when i connect a speaker to the board

0 TommyG over 14 years ago in reply to habeeb siddique37664

TI__Genius 13045 points

Habeeb,

I think the reason the numbers aren't the same is that you are not sampling the analog signal at exactly relative time on the receiving DSK. Since you are using Line OUT that means you are sending the digital signal first through an audio codec that converts the signal to analog and does some filtering to smooth the output. The reverse happens on the Line IN signal. So even though the audio sounds the same to you , if you were to look at the numbers in the sending and receiving buffers, they would not be the same either. If you want exact data to be transmitted, you would need to use one of the serial interfaces available on the DSP. Those are only pinned out the the daughterboard connector on this board.

Hope this helps.

Regards.

0 habeeb siddique37664 over 14 years ago in reply to TommyG

Intellectual 640 points

Hi TommyG,

How much will the numbers change, do they change by maximum difference of +30 , -30 units.

0 TommyG over 14 years ago in reply to habeeb siddique37664

TI__Genius 13045 points

Habeeb,

I don't know that there is anyway to tell. Think of a sine wave. According to Nyquist you only need to sample twice per cycle to be able to reconstruct. If one person samples at the peaks and another person samples at a different location on the sine wave it could be almost p-p of the signal difference. Worst case being sampling at the zero crossings.

I think if you really need bit exact transfers, then you need to use one of the interfaces that let's you transfer digital data without the analog translations. If you have to use an audio interface, then you may want to consider some type of coding scheme (like used in a telephone modem). Maybe some of the signal processing experts could give you a better answer.

Regards.

0 habeeb siddique37664 over 14 years ago in reply to TommyG

Intellectual 640 points

if i increase the sampling rate i should be having a lower difference between the sent value and received value.

am i right

0 habeeb siddique37664 over 14 years ago in reply to habeeb siddique37664

Intellectual 640 points

do we have any frame synchronization options in the dsp

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values in the G buffer and the are not getting through