Texas DSP 2812 and McBSP

Digital Signal Processing

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    Hello all, Does anyone know an IIR form that would prevent/reduce the effects o limit cycles? Just so everyone is clear about what I mean when I sa "limit cycles": It is the phenomena whereby fixed point DSP's cannot quantize very precis multiplies within a feedback (a-terms) mac's of an IIR filter. This ca cause what appears to be moments of instabilities at very low inpu levels. (only a couple of lsb's toggling) a.k.a. small scale limi cycles. In the audio processing wold, I've seen this manifest itself as subwoofer grumbling when several low cutoff LPF's were used in series. I was essentially reacting to the noise floor of the A/D converters an providing a signal much louder than the input. I have heard from another DSP Engineer that there is an IIR form tha reduces the effect of limit cycles so that it is barely noticable. Toda we use double-precision data storage to eliminate this problem, but I wan to remove this MIPS hit if possible. Any ideas? Jeff
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  • 3. OT - major quake prediction dec 2007
    ---------- Forwarded message ---------- From: Mana Kannu < XXXX@XXXXX.COM > Date: Dec 20, 2007 2:44 AM Subject: Major Earthquake prediction Dec 2007 To: - Hide quoted text - Sub : Major Earthquake that can outperform 2004-Sumatra is predicted to occur between 23-dec and 29-dec 2007, by an Indian Astrologer Mr Natarajan. Location : "The pacific ring of fire region" - Indonesia, Japan, Taiwan, Phillipines Magnitude : Worst than 2004 sumatra, huge casuality. Dec-23rd, 2007 - Most probable date of strike as per Vedic Astrology. More details : manakannu.blogspot.com Whether to treat this as a spam and brush it aside is up to you. But just remember that Dec-23, 2007 is just a few days after. The Onus is up to you to act, if you consider this prediction worth while. Atleast you could warn the countries expected. I know that there is no scientific reason as per modern world standard to put-forth. However truth can be more mysterious. Sorry to have intruded. I need to answer my conscience. -manakannu
  • 4. bartlet
    hi folks, i have a term project about high-pass bessel filter with fstop 200Hz and fPass = 400Hz, there's no big deal in "iir" design, i coul overcome it, but at the "fir" design i was asked to perform this by "bartlett window" and my brain is almost to explode, i can't find an articles, any techniques and unfortunately there's no assistants to hel me (and as we all know "if you don't know well enough sth., you'd bette don't know":) )... i'm looking for your answers... thank you all..

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.


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?


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 ?


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.

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

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

Dose someone know how to accomplish this task?

Thanks a lot for your answers

3.own api flashing dsp 2812

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.

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


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

6. Matlab GUI for coupling TI 2812 DSP with Simulink RTW

7. ADC using 2812

8. flash and external ram timing on TI 2812

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