Forums

Fwd: 12-bit ADC with C6713

Started by "varoonian ." December 22, 2010
Thanks BS. So the 5-6 K Board fits with the EMIF ??
On Wed, Dec 22, 2010 at 3:58 AM, B S wrote:

> Thanks guys for your answers.
>
> @ R. Williams,
>
> I don't think that much RAM is available. I am using C6713 DSK with 16 MB
> SDRAM, L1P is 4K-Bytes and L1D is 4K-Bytes while L2 memory is 256K-Bytes.
>
> I am using ADS7881EVM.
>
> ADS7881EVM has been interfaced through a 5-6K Interface Board to DSP.
>
> Since ADC is unipolar, I am using offser Voltage of 1V controlled by
> ADS7881.
>
> ADC is 12 bit device while DSP is saving sampled values in unsigned short
> format. Check out the amplitude level of sampled sine wave in the snapshot
> given below, I don't know how DSP is doing mathematics to convert 12 bits to
> 16 bits. I really don't know how to scale the output.
>
> http://i55.tinypic.com/21d51ty.jpg
>
> #pragma DATA_ALIGN (r_buffer, 128)
> unsigned short r_buffer[BUFFER_SIZE];
>
> I don't know how transfer of data from DSP to PC will take place, heard
> about RTDX but don't know how it works. Any help regarding that will be
> appreciated. Size of the data is not a problem even 1024 samples will be
> enough but I want to examine them in Matlab.
>
> @ Voranian
>
> I am using 5-6K Interfacing Board to interface ADS7881 Evaliation Module
> with C6713.
>
> @ Mikedunn
>
> Don't know much about SDRAM, but I will see how to do it.
> ---------
>
> Waiting for your response.
>
> -BAS
>
> ------------------------------
> *From:* Richard Williams
> *To:* B S ; c...
> *Sent:* Wed, December 22, 2010 12:43:25 AM
> *Subject:* Re: [c6x] 12-bit ADC with C6713
> B.S.
>
> a 5Khz input signal will require a(at least) a 10khz sampling rate to avoid
> problems with the nyquist(sp) frequency.
> I think the next higher sampling rate available is 16khz.
> so 16k*60*5H00000 samples in 5 minutes.
> at 4 bytes per sample= 19,200,000 bytes of RAM
> That is nearly 20megs of RAM.
> (you might be able to use 'short' (16bit) values, which would cut the RAM
> used
> by half)
>
> Do you have that much RAM available?
>
> You did not mention which ADC you are using.
> You did not mention how the ADC is actually attached to the DSP.
> You did not mention how you are handling the negative voltage values.
>
> That info would be useful in determining the expected range of the data
> values
> in RAM and if any pre-scaling or level shifting of the voltages will be
> needed
> in hardware.
>
> I expect you will need to shift the voltage levels both for the input and
> for
> the output.
> I expect you will need to scale the voltage levels both for the input and
> for
> the output.
>
> How do you plan on getting the data from the DSP RAM to MatLab?
> RTDX, DAC, something else?
>
> Such details will make a significant difference in how the RAM data will
> need to
> be scaled, level shifted, etc. before being sent out.
>
> R. Williams
>
> ---------- Original Message -----------
> From: B S >
> To: c...
> Sent: Tue, 21 Dec 2010 11:57:59 -0800 (PST)
> Subject: [c6x] 12-bit ADC with C6713
>
> > Hi,
> >
> > I have interfaced a 12-bit ADC with C6713 DSP. How can I scale the
> > output to see the amplitude of the output signal same as of input
> > signal ? For example, Amplitude = 2 Vp_p with 5KHz frequency ?
> >
> > I want to run ADC for 5 minutes or more and save all the sampled
> > values in a file to examine them in Matlab ? Can you please tell me
> > how could I do it ?
> >
> > Waiting for your help.
> >
> > BR,
> > BAS
> ------- End of Original Message -------
>
>

--
Varun

--
Varun
Varun,

On 12/22/2010 9:40 AM, varoonian . wrote:
>
> Thanks BS. So the 5-6 K Board fits with the EMIF ??

YES.

mikedunn
> On Wed, Dec 22, 2010 at 3:58 AM, B S > > wrote:
>
> Thanks guys for your answers.
>
> @ R. Williams,
>
> I don't think that much RAM is available. I am using C6713 DSK
> with 16 MB SDRAM, L1P is 4K-Bytes and L1D is 4K-Bytes while L2
> memory is 256K-Bytes.
>
> I am using ADS7881EVM.
>
> ADS7881EVM has been interfaced through a 5-6K Interface Board to DSP.
>
> Since ADC is unipolar, I am using offser Voltage of 1V controlled
> by ADS7881.
>
> ADC is 12 bit device while DSP is saving sampled values in
> unsigned short format. Check out the amplitude level of sampled
> sine wave in the snapshot given below, I don't know how DSP is
> doing mathematics to convert 12 bits to 16 bits. I really don't
> know how to scale the output.
>
> http://i55.tinypic.com/21d51ty.jpg
>
> #pragma DATA_ALIGN (r_buffer, 128)
> unsigned short r_buffer[BUFFER_SIZE];
>
> I don't know how transfer of data from DSP to PC will take place,
> heard about RTDX but don't know how it works. Any help regarding
> that will be appreciated. Size of the data is not a problem even
> 1024 samples will be enough but I want to examine them in Matlab.
>
> @ Voranian
>
> I am using 5-6K Interfacing Board to interface ADS7881 Evaliation
> Module with C6713.
>
> @ Mikedunn
>
> Don't know much about SDRAM, but I will see how to do it.
> ---------
>
> Waiting for your response.
>
> -BAS
>
>
> *From:* Richard Williams > >
> *To:* B S >;
> c...
> *Sent:* Wed, December 22, 2010 12:43:25 AM
> *Subject:* Re: [c6x] 12-bit ADC with C6713
> B.S.
>
> a 5Khz input signal will require a(at least) a 10khz sampling rate
> to avoid
> problems with the nyquist(sp) frequency.
> I think the next higher sampling rate available is 16khz.
> so 16k*60*5H00000 samples in 5 minutes.
> at 4 bytes per sample= 19,200,000 bytes of RAM
> That is nearly 20megs of RAM.
> (you might be able to use 'short' (16bit) values, which would cut
> the RAM used
> by half)
>
> Do you have that much RAM available?
>
> You did not mention which ADC you are using.
> You did not mention how the ADC is actually attached to the DSP.
> You did not mention how you are handling the negative voltage values.
>
> That info would be useful in determining the expected range of the
> data values
> in RAM and if any pre-scaling or level shifting of the voltages
> will be needed
> in hardware.
>
> I expect you will need to shift the voltage levels both for the
> input and for
> the output.
> I expect you will need to scale the voltage levels both for the
> input and for
> the output.
>
> How do you plan on getting the data from the DSP RAM to MatLab?
> RTDX, DAC, something else?
>
> Such details will make a significant difference in how the RAM
> data will need to
> be scaled, level shifted, etc. before being sent out.
>
> R. Williams
>
> ---------- Original Message -----------
> From: B S >
> To: c...
> Sent: Tue, 21 Dec 2010 11:57:59 -0800 (PST)
> Subject: [c6x] 12-bit ADC with C6713
>
> > Hi,
> >
> > I have interfaced a 12-bit ADC with C6713 DSP. How can I scale the
> > output to see the amplitude of the output signal same as of input
> > signal ? For example, Amplitude = 2 Vp_p with 5KHz frequency ?
> >
> > I want to run ADC for 5 minutes or more and save all the sampled
> > values in a file to examine them in Matlab ? Can you please tell me
> > how could I do it ?
> >
> > Waiting for your help.
> >
> > BR,
> > BAS
> ------- End of Original Message -------
>
> --
> Varun
>
> --
> Varun
>
Thanks Mr.Dunn. One more question I have is the 5-6 K interface has only one
parallel databus.

Which means you can fit either the EMIF or McBSP to the 5-6 K interface.

What if you need the EMIF out clock and EMIF control signals ? One board
will not suffice or you might need to use a separate wire for the clock.

According to the datasheet the EMIF out clock is on the McBSP if I am
correct.

Thanks,

On Wed, Dec 22, 2010 at 11:06 AM, mikedunn wrote:

> Varun,
> On 12/22/2010 9:40 AM, varoonian . wrote:
>
> Thanks BS. So the 5-6 K Board fits with the EMIF ??
>
>
> YES.
>
> mikedunn
>
> On Wed, Dec 22, 2010 at 3:58 AM, B S wrote:
>
>>
>> Thanks guys for your answers.
>>
>> @ R. Williams,
>>
>> I don't think that much RAM is available. I am using C6713 DSK with 16 MB
>> SDRAM, L1P is 4K-Bytes and L1D is 4K-Bytes while L2 memory is 256K-Bytes.
>>
>> I am using ADS7881EVM.
>>
>> ADS7881EVM has been interfaced through a 5-6K Interface Board to DSP.
>>
>> Since ADC is unipolar, I am using offser Voltage of 1V controlled by
>> ADS7881.
>>
>> ADC is 12 bit device while DSP is saving sampled values in unsigned short
>> format. Check out the amplitude level of sampled sine wave in the snapshot
>> given below, I don't know how DSP is doing mathematics to convert 12 bits to
>> 16 bits. I really don't know how to scale the output.
>>
>> http://i55.tinypic.com/21d51ty.jpg
>>
>> #pragma DATA_ALIGN (r_buffer, 128)
>> unsigned short r_buffer[BUFFER_SIZE];
>>
>> I don't know how transfer of data from DSP to PC will take place, heard
>> about RTDX but don't know how it works. Any help regarding that will be
>> appreciated. Size of the data is not a problem even 1024 samples will be
>> enough but I want to examine them in Matlab.
>>
>> @ Voranian
>>
>> I am using 5-6K Interfacing Board to interface ADS7881 Evaliation Module
>> with C6713.
>>
>> @ Mikedunn
>>
>> Don't know much about SDRAM, but I will see how to do it.
>> ---------
>>
>> Waiting for your response.
>>
>> -BAS
>>
>> ------------------------------
>> *From:* Richard Williams
>> *To:* B S ; c...
>> *Sent:* Wed, December 22, 2010 12:43:25 AM
>> *Subject:* Re: [c6x] 12-bit ADC with C6713
>> B.S.
>>
>> a 5Khz input signal will require a(at least) a 10khz sampling rate to
>> avoid
>> problems with the nyquist(sp) frequency.
>> I think the next higher sampling rate available is 16khz.
>> so 16k*60*5H00000 samples in 5 minutes.
>> at 4 bytes per sample= 19,200,000 bytes of RAM
>> That is nearly 20megs of RAM.
>> (you might be able to use 'short' (16bit) values, which would cut the RAM
>> used
>> by half)
>>
>> Do you have that much RAM available?
>>
>> You did not mention which ADC you are using.
>> You did not mention how the ADC is actually attached to the DSP.
>> You did not mention how you are handling the negative voltage values.
>>
>> That info would be useful in determining the expected range of the data
>> values
>> in RAM and if any pre-scaling or level shifting of the voltages will be
>> needed
>> in hardware.
>>
>> I expect you will need to shift the voltage levels both for the input and
>> for
>> the output.
>> I expect you will need to scale the voltage levels both for the input and
>> for
>> the output.
>>
>> How do you plan on getting the data from the DSP RAM to MatLab?
>> RTDX, DAC, something else?
>>
>> Such details will make a significant difference in how the RAM data will
>> need to
>> be scaled, level shifted, etc. before being sent out.
>>
>> R. Williams
>>
>> ---------- Original Message -----------
>> From: B S >
>> To: c...
>> Sent: Tue, 21 Dec 2010 11:57:59 -0800 (PST)
>> Subject: [c6x] 12-bit ADC with C6713
>>
>> > Hi,
>> >
>> > I have interfaced a 12-bit ADC with C6713 DSP. How can I scale the
>> > output to see the amplitude of the output signal same as of input
>> > signal ? For example, Amplitude = 2 Vp_p with 5KHz frequency ?
>> >
>> > I want to run ADC for 5 minutes or more and save all the sampled
>> > values in a file to examine them in Matlab ? Can you please tell me
>> > how could I do it ?
>> >
>> > Waiting for your help.
>> >
>> > BR,
>> > BAS
>> ------- End of Original Message -------
>>
> --
> Varun
>
> --
> Varun
>
--
Varun