Prabhu-
> ours is an audio related product which contains 3
c672x dsps connected in daisy
> chain.
> we are debugging with engineering prototype.am facing a strange problem.c672x
dsp
> works fine(load and run) with PP+ emulator.
> but doesnt work with usb emulator. 1. Found that the dsp board gets connected
and
> works well with PP+ emulator.
> with with usb emulator, even we were not able to get connected. 2. after
> investigating found that system power supply was culprit.now we are
> providing separate power supply to dsp board. 3. now the new problem is
when we
> use PP+ emulator all the three dsps works fine.but if we use
> usb emulator only the middle dsp is not working other two 1st and 3rd are
working
> good.not working means we can connect to dsp using ccs, can download program
but
> if
> we run then no output is observed.we have designed the jtag circuit according
to
> ti
> application notes.power supply is fine. dsp power is fine.it is not
software
> problem as
> it works good(can get audio o/p) with PP+, EMU0/1 are high, tck clock is
> fine,believe
> tdi/tdo is fine as sdconfig test passes. please let me know is there anything
else
> to be checked. PS: we never faced this problem in design prototype. there both
PP+
> and usb are working good.
1) Which emulator? Some vendors have known issues with USB vs. parallel port
versions, or vice versa.
2) This is likely a signal integrity issue:
-suggest to check TCK in particular to make sure it's rise-time
is sharp with no noise that could lead to glitches or possible
double-clocking on the second DSP
-how long is the TDI-TDO data path? If this becomes several cm
due to multiple devices, that could be a problem
-where do you pick off TCK_RET signal? If you're doing this
at the JTAG header, you should try getting it from the
furthest of the 3 DSPs away from the header
3) SDConfig test is not enough. Suggest to try xdsprobe.exe for more rigorous
test
of scan path.
-Jeff