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KR1S
PostPosted: Mon Nov 21, 2011 12:29 am 
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The TMDX5535eZdsp is a small form factor, very low cost USB-powered DSP development kit which includes all the hardware and software needed to evaluate the C553x generation, which is the industry’s lowest-cost and lowest power 16-bit DSP. This ultra-low-cost kit allows quick and easy evaluation of the advanced capabilities of the C5532, C5533, C5534 and C5535 processors. The kit has an on-board XDS100 emulator for full course-level debug capability and supports Code Composer Studio™ (CCStudio) Integrated Development Environment (IDE) version 4.x and eXpressDSP™ software which includes the DSP/BIOS™ kernel. The full contents of the Development Kit include C5535 ezdsp board, CCStudio IDE Rev. 4.x, and headphone with mic, a 2-GB micro SD card, a free software framework for USB audio class and human interface device (HID) applications and an out-of-the-box comprehensive demo for USB audio class applications. Ordering Information: Available now for $55* (a $44 savings) – normally priced at $99 USD.

*Offer has been extended through December 31, 2011.

http://www.ti.com/tool/tmdx5535ezdsp

73,

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qrp-gaijin
PostPosted: Mon Nov 21, 2011 3:14 pm 
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KR1S wrote:
Available now for $55* (a $44 savings) – normally priced at $99 USD.

I spent almost that much on a variable capacitor.

Can this unit function standalone without a PC after it's been programmed? If not, what is needed to make a standalone DSP unit for use with a radio?
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KR1S
PostPosted: Mon Nov 21, 2011 3:49 pm 
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qrp-gaijin wrote:
KR1S wrote:
Available now for $55* (a $44 savings) – normally priced at $99 USD.

I spent almost that much on a variable capacitor.

Can this unit function standalone without a PC after it's been programmed? If not, what is needed to make a standalone DSP unit for use with a radio?

From reading the description, it's contained in a USB plug, so I guess it needs a PC to function. A standalone DSP would need a processor and I/O ports. I suppose you could program a PIC but that would make it difficult to adjust the functions once programmed. TI's been doing DSP for decades, so they probably have a good system here.

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qrp-gaijin
PostPosted: Tue Nov 22, 2011 4:43 am 
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KR1S wrote:
From reading the description, it's contained in a USB plug, so I guess it needs a PC to function. A standalone DSP would need a processor and I/O ports.

If it needs a PC to function, then is there any benefit in doing the DSP on the board as opposed to doing the DSP on the PC?
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KR1S
PostPosted: Tue Nov 22, 2011 12:39 pm 
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qrp-gaijin wrote:
KR1S wrote:
From reading the description, it's contained in a USB plug, so I guess it needs a PC to function. A standalone DSP would need a processor and I/O ports.

If it needs a PC to function, then is there any benefit in doing the DSP on the board as opposed to doing the DSP on the PC?

My PC is big and heavy! It's a development kit. Presumably, when you have the code you want you buy more parts from your nice TI distributor, burn some code into them, and wrap it in a box. This is a cheap way to play with high-end DSP.

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vladn
PostPosted: Tue Nov 22, 2011 5:18 pm 
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qrp-gaijin wrote:
If it needs a PC to function, then is there any benefit in doing the DSP on the board as opposed to doing the DSP on the PC?

The board has 8Mb of serial flash so most likely it can operate standalone. There is no power jack (power is supplied via USB) but this can be easily fixed. On-board codec is 48ksps only, not the best for SDR but still usable for experimenting.
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qrp-gaijin
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PostPosted: Tue Nov 22, 2011 7:23 pm 
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Any idea if the signal outputs (and less importantly, the inputs) are DC-coupled?
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vladn
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PostPosted: Tue Nov 22, 2011 7:31 pm 
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According to the schematics it is AC coupled, but that probably can also be fixed with a bit of soldering. There is a reference manual for the board:
http://support.spectrumdigital.com/boar ... f_RevC.pdf
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qrp-gaijin
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PostPosted: Wed Nov 23, 2011 1:55 pm 
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Is it pretty easy to program this kind of chip to make an audio phase shift network for a phasing DC receiver? Any pointers to sample code? Combined with something like TinySDR, this might make a simple and small receiver. I wonder about the power consumption though. I didn't see that mentioned in the docs.
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KR1S
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PostPosted: Wed Nov 23, 2011 3:10 pm 
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qrp-gaijin wrote:
I wonder about the power consumption though. I didn't see that mentioned in the docs.

Isn't it powered off the USB port?

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kenn
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PostPosted: Wed Nov 23, 2011 7:02 pm 
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Thanks for posting this deal. Besides radios, I also like to mess with microcontrollers (mostly PICs), and I've thought about looking at DSPs, since I also have a background in audio. :). This offer might be irresistible...

[edit] yes - it was irresistible. :) ordered one.
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vladn
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PostPosted: Wed Nov 23, 2011 8:08 pm 
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qrp-gaijin wrote:
Is it pretty easy to program this kind of chip to make an audio phase shift network for a phasing DC receiver? Any pointers to sample code?

If you never done DSP programming there is quite a bit of a learning curve, but if you have plenty of time - go for it. For audio phase shift network search for Hilbert transform code examples.
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qrp-gaijin
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PostPosted: Wed Nov 23, 2011 10:21 pm 
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KR1S wrote:
qrp-gaijin wrote:
I wonder about the power consumption though. I didn't see that mentioned in the docs.

Isn't it powered off the USB port?

The docs seem to hint at the possibility that it can be operated stand-alone, in which case it becomes interesting how much current the device actually draws, for portable battery-powered use. Any educated guesses?
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KR1S
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PostPosted: Wed Nov 23, 2011 11:51 pm 
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qrp-gaijin wrote:
The docs seem to hint at the possibility that it can be operated stand-alone, in which case it becomes interesting how much current the device actually draws, for portable battery-powered use. Any educated guesses?

It would run off a USB supply like the one for my phone. According to Wikipedia, "USB current (related to power) is allocated in units of 100 mA up to a maximum total of 500 mA per port." My phone's charger, OTOH, will source up to 700 mA.

http://en.wikipedia.org/wiki/USB_hub

Guess you could email TI and ask.

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qrp-gaijin
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PostPosted: Thu Nov 24, 2011 4:33 am 
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vladn wrote:
If you never done DSP programming there is quite a bit of a learning curve, but if you have plenty of time - go for it. For audio phase shift network search for Hilbert transform code examples.

OK, that's a start. Forgive the basic questions, but this is all quite new (and fascinating) to me. I'm wondering what I can reasonably expect a unit like this to do. I've experimented with some DSP software on my PC, but if this little standalone unit can do even some of the things my PC can do, then it might be very useful indeed.

For instance, is it reasonable to expect to be able to do the following on the unit?
- normal (infinite impulse response?) audio filtering: bandpass, low pass, high-pass, notch, with up to 10 or more poles, and multiple chained filters
- finite-impulse response filtering (no ringing)
- envelope detection of AM signals
- Costas loop
- AGC
- decoding CW/PSK/RTTY/digimodes to text (using the unit's on-board LCD display)
- spectral analysis of audio signal (e.g. to detect Q multiplier bandwidth)

Are there libraries for this kind of programming, or does everything have to be coded from first principles?
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