I'm about to design a PCB for a project with a TI DSP (TMS320C6720). What is the best method to use as an interface for getting the program onto the DSP? I haven't done this part myself before. I'll be using CCS v4 and my motherboard has usb 2.0 pots and a parallel port but I'd rather use the USB so that I could keep using whatever cable I need to get in the future. I'd prefer a low cost solution, I saw some JTAG emulators that cost 100's which is more expensive than I thought would be necessary, however it would be helpful to be able to debug when I'm programming. Thanks
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Would one of the USB ezdsp sticks work as a replacement for the JTAG? At least you can have a look at the schematics to see how those do the programming interface.
TI's documentation is really dense, especially outside MSP430 realm. The DSP's still seem to be firmly in deep pockets territory having expensive tools and proprietary compilers and hard to get information.
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I speak from a somewhat outdated background; years ago I designed a DSP card for the PC ISA architecture ; the DSP was a TMS320C25, and I used 10 ns static RAM. The interface was a 'dual port' approach, where the DSP's hold mode was invoked, tri-stating the 16 bit data bus, the address bus, and control lines. The memory was buffered by 74HC245's from both the DSP and the PC bus; invoking the DSP hold gated access to allow PC access. The DSP's memory was mapped to the PC's UMB area at 0xD000:0000 for a 64K byte size. This required attention to byte sequence during word transfers, as the DSP uses 16 bit word sizes. I wrote the assembler (using 'C') to handle this, and it worked well. The ISA bus is outdated, now, but the PCI bus is somewhat similar, and should, perhaps, allow a similar approach. However, I have not attempted a more recent design, so approach carefully.... Hope this is of some use to you...! Perhaps, another approach, would be to use an additional micro-controller on your board to accept USB data, and transiently access the DSP memory for data, code placement.
