Suggestions for JTAG that's fast at single step debugging?
I currently use a pair of Stellaris ICDI JTAG devices for programming and debugging ARM devices. I have no real problem with the download speed, but single stepping is far too slow. If I'm single stepping through C code in Visual Studio on the PC, it steps from line to line pretty much instantly. With the ARM and JTAG, each steps takes about a second. That doesn't sound too bad, but I single step through pretty much every line of my code. That makes it pretty awful to use
I'm not sure if the debug speed issue here is the Stellaris JTAG device (which uses the FTDI serial chip), or JTAG in general. I don't want to just buy something without hearing from others who have used it.
Any suggestions for a JTAG device which can single step quickly? Ideally, quick stepping means it moves from line to line as fast as I click the mouse. Also, if it can get into and out of debug mode quickly, that would also be a plus.
Thanks
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FTDI-based devices are great when blasting in one direction (writing), but suffer from USB latencies when reading. Basically, to read something, like memory, you need to write a command, wait for a the next USB slot to read, wait for the next to write, and those slots are 1ms apart. So, programming is fast, but reading back memory is slow.
I suggest getting something with intelligence, such as a CrossConnect... :-) When reading, the read is done in the box, closer to the micro, and not hand-constructed on the PC. However, backtracing requires quite a bit of reading, as does populating the Threads window if you're running a script. But a CrossConnect will certainly be faster!
Regards,
-- Paul
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