Thank You very much for your reply.I really felt more enlightnd after that (really).had a tough time finding the answer through the web
You are welcome! I'm happy for being able to give you a little guidance.
Does it mean that we can do this JTAG programming for a single chip after it has been soldered to the PCB with the allocation for a JTAG programming port to the single chip?
Yes. This is what we normally do with micros, isn't it? If we solder a micro to the board (rather than on a base to for ADC applications), we leave the ISP port on the custom PCB. So whenever we want, we can program. Just like that we keep the JTAG port for both Atmel and dsPIC chips.
However, as I have already told you, soldering DSP is a challenge (I have never seen DIP packages... All I have seen are QFP and BGAs). I recommend you to start with an evaluation module. However, if you really want to start by your own, you might use a QFP test socket as follows. But this is not even possible with BGA chips.
- socket.png (179.63 KiB) Viewed 13698 times
And does this mean that an evaluation board or a USB stick will be necessary for prototyping?( which is easier with a DIP package PIC and Breadboards).
For prototyping, you can either buy an evaluation board or make your own one as discussed above. You will need that JTAG emulator and the programming software as well.
I also heard that external memory should be used if the program code is too large. if so how is it that the dsp if programmed to fetch these instructions from the external memory(i.e. does the dsp have this capability? i really don't know)?
Not all but some have the capability to access external memory. However, external memory requirement is only for very large applications. DSPs have quite a lot of in-built memory than dsPICs or micros. So for 90% applications, it is enough. When you have an evaluation module and you program on it, on the final phase you can decide what exactly you need on the final hardware.
Also, you need to decide which DSP you are going to use. Based on that only you can buy the evaluation module. Like micros, there are no such board which you can program multiple types of chips.
Following docs might help you.
http://www.bdti.com/MyBDTI/pubs/choose_2000.pdf
http://www.bdti.com/MyBDTI/pubs/20060405_ESC06_dsps.pdf
With this Ti page, you'll be able to select a Ti processor.
http://www.ti.com/lsds/ti/dsp/platform/device.page