dsPIC - DSP - digital signal processing proejcts

[Garyl]

Hey,
can someone in a simple words tell me what I can do with dsPIC that I can't do with other PIC?
Can you recommend me some interesting DSP projects that I can do?
Timeframe is not really important, I just want to know what I can use especially the DSP for.
Thanks in advance!

 

[Aussie Susan]

The Microchip dsPIC33 families of devices are almost exactly the same as the PIC24 families and many of them use the same peripheral designs and the same core (and hence instruction set).
The difference is that the dsPIC33 devices has an additional 'multiply/accumulate' capability and special registers and memory access modes that let it perform multiply/accumulate operations common in signal processing. Typically you have two arrays of values that you want to multiply corresponding items together and then sum the result and the DSP hardware lets you set up this situation and have it operate much faster than trying to write loops and pointer update code yourself. The input and output memory array pointers can be set up to auto-loop back whent hey get to the end/start of the array.
Also the accumulation register is typically 40 bits long so it can handle the integer multiplications (note that the Microchip DSPs are not floating point processors - but they do handle fixed point number extremely well) and accumulation with out overflows in many cases.
They can be used for DFT calculations, convolution/correlation calculations (with special modes for cases where a pointer moves back backwards), digital filters and the like.
As for projects, it all depends on what yo are interested in. If you want to perform a frequency analysis of (say) an audio signal then coding a DFT algorithm would be useful - perhaps you want to create a digital equaliser. If you want to up/down-sample audio you will then need to apply an interpolation or decimation filter - with both processes being done by the DSP component. There are many more cases.
Susan