Texas DSP 2812 and McBSP

Digital Signal Processing

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  • 1. Profiling
    Hello, Can someone explain what are the column headings in the profile window? I step through the Tutorial which explain briefly how to use profiling but it doesn't really explain what are the different column headings for.
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    The "frequency response of a PLL" is plotted as angle_at_vco_output(s)/angle_of_input_wavefom(s) = a classical 2nd order system described by a the "s" transform, where s = jw. Where w is in radians. So what does a plot of this convey. I've read in places that we can interpret the response as a low pass filter etc. But what we have here is not input voltage divided by output volatage, but input angle divided by "output angle". Ted.
  • 3. Help proving theorom
    I have a theorom I am trying to prove, that is part of a proof for a more important theorom. I hope that someone whose math skills exceed mine can help! Start with: 1) Given an infinite-energy signal v(t) (which could be either discrete or continuous-time) 2) Define the average power of this signal in the usual way; Power = limit as T approaches infinity of ; (1/T)* (Integral from t=0 to t=T of v(t)^2 dt) Theorom: If the average power of v(t), as defined above, does not converge to a constant as T approaches infinity, then the Fourier transform F(w) = FT(v(t)) cannot have any zeros (that is, values of w where F(w) is zero). The intuitive reasoning behind this is that any signal that does not have constant average power over time must have spectral components that are either decaying or growing, and these changing spectral components implies spectral smearing which will tend to fill in any zeros. Anyone care to tackle this one? Regards Bob Adams
  • 4. Digital down converter
    Hi, I am working on the DDS section of the digital down converter. I have instantiated nco (sine wave generator) generated from Xilinx core generator generating perfect sine wave which is an input to a multiplier18*18S( available in Virtex-II), a DCM which multiplies the incoming clock of 40Mhz by 2, and a module which has been written to send the data out from the multiplier to a FIFO and then this data is sent to a COM port at a slower rate. Multiplier and the FIFO works at 80 MHZ and the module that sends the data to the COM port works on a divided 40 MHZ clock to get the appropriate baud rate. I have downloaded the design to Xilinx Virtex-II Evaluation kit by Avnet design services. When I give the incoming data (second input of the multiplier) from an internal register data_reg = "001111111111111111" I get a noisy waveform at the output of the multiplier (when viewed in MATLAB). When I give data_reg = "0000000000000001" I get perfect sine wave at the output. When I give the data from Analog Devices A/D converter AD6645, instead of an internal register data_reg, it works if I connect only DIN<0> and DIN<1> through UCF file. But if I connect DIN<2> and other higher bits I get noise at the output. Could you please suggest why this is happening. Any help will be appreciated. Thanks Ritu

Texas DSP 2812 and McBSP

Postby Torgeir Jakobsen » Thu, 02 Dec 2004 02:40:47 GMT

Hi all DSP experts :-)

I have a problem with the McBSP receive interrupt on the 2812 DSP from
Texas. Do anyone have working code on this DSP ?
I have done much the same as on the 5510 DSP where I did not have this
problem, so I do not understand why it is not working here ?

Thanks in advance.

Torgeir



Re: Texas DSP 2812 and McBSP

Postby Brad Griffis » Thu, 02 Dec 2004 10:44:32 GMT

There are more things you need to enable to get interrupts on the 2812 than 
there are on the 5510.  Are you sure that you have enabled the PIE, set the 
proper bit in the PIEIER for the McBSP interrupt, acknowledged the PIE 
(PIEACK), set the corresponding IER bit, and cleared the INTM bit?

Also, are you sure that you have configured the McBSP to generate a receive 
interrupt?  Are you seeing the RRDY flag which indicates there is data in 
the McBSP to be read?

Brad








Re: Texas DSP 2812 and McBSP

Postby Torgeir Jakobsen » Thu, 02 Dec 2004 18:55:30 GMT

Thank you Brad,

I have done the things you describe:
- Enabled PIE
- Set PIEIER for McBSP receive interrupt
- Acknowledged the PIE
- Set IER
- Cleared INTM.

First it looked like RRDY was not set, but now the RRDY is set. I have also
enabled the transmit interrupt to see if this was working better.  I can see
that RRDY and XRDY is set but the PIEIFR register (and PIEACK) does not flag
any interrupt, even if McBSP is set to generate interrupt on RRDY and XRDY
and the PIEIER is set to enable both interrupts.
I am using the sample rate generator, and the clock and frame signals are
generated correctly (measured with oscilloscope).

Any suggestions ?






than
the
receive






Similar Threads:

1.McBSP interrupts on Texas 2812

I have problems with the receive and transmit interrupts on this DSP. I have
set the McBSP to generate interrupts on RRDY and XRDY, and I can see that
these bits are set when I emulate the program on my hardware (using XDS510PP
Plus and CCS). This should also have activated the corresponding interrupt
flags in the PIEIFR6 regsiter (bit 5 and 6), but this does not happen.
I can see that my ISRs are working if I set the interrupt flags in PIEIFR6
manually, so the problem is the connection between the McBSP and the PIEIFR6
register. What do I have to do to make the McBSP RRDY and XRDY activate the
flags in PIEIFR6 ?
I use the internal sample rate generator, and I can see the frame and clock
signals with my oscilloscope.

Thank you in advance.

2.hwo to set up interrupt in dsp 2812

Hi everyone!
I am new in using dsp 2812.

I want to make an T3PINT interrupt.

I just read "TMS320x281x DSP System Control and Interrupts Reference
Guide"(spru078e) and
"TMS320x281x DSP Event Manager (EV) Reference Guide"(spru065e),

On page 84 in spru065e,and on page 122 in spru078e,
what's mentioned in the priority field seems different.
Why?

I am traceing the C of the example "sw_prioritized_interrupts"
mentioned in the document "C281x C/C++ Header Files and Peripheral
Examples".

It seems that cpu branchs to ISR to setup priority.Is this the way it
does? Or Is my understanding wrong?
(FILE:   DSP281x_SWPiroritizedPieVect.c)

If priority can be set in code,why priority are mentioned in these
document?

Dose someone know how to accomplish this task?

Thanks a lot for your answers
Bell

3.own api flashing dsp 2812

Hello,
I work on  a 2812 dsp board, I make a c# application to test it and now 
want to flash it.

On this board i have four Dsp (not interconnected), i use SDFlash wit
four com port and four sdp project.

I can create a process which will launch four SDFlash.
Does SdFlash can take arguments in a command line, like this ?
\SdFlash clientprjCom1.sdp
...
\SdFlash clientprjCom4.sdp

An other idea is to create my own window working like SDFlash.
In this case, do you know if it's possible to have SDFlash source code
or informations about c++ input methods that i can call to flash dsp.

A last question, does it exist an industrial method to flash more fastly
several dsp.

thank you for your help.
Laurence




4.ADC's noise on DSP 2812

Hi everybody !!!

Can someone help me to solve the following problem ?
I need to use an external signal in my program in order to make a goo
enslavment of a signal.
So what, i want to get a very accurate value of my external signal.
I use the ADC module of the DSP 2812 but when I look a the value returne
there's a lot of noise on it.
Can someone explain me why this measure is so noisy and how i coul
improve it ?
Thanks a lot

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5.DSP-2812: Calling SCI_BOOT from the program

Hi All,

I want to call SCI_BOOT in my program in order to use SDFlash to update
the flash. The resistors are set up in such a way that it boots from
flash and I don't want to change that. Or can the DSP-resetted in such
a way that it ignores the hardware and boots from SCI_BOOT anyway.

Kind regards, Frank

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7. ADC using 2812

8. flash and external ram timing on TI 2812



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