I am trying to figure out why a TMS320F28035 DSP is not communicating with an XDS510LC USB emulator. When I initiate and emulation reset (from SDFlash), I get the following sequence:
- TCK starts clocking and TDI goes high (TDO is already high)
- TRST goes high
- TMS starts pulsing
- TDO and TDI remain high
On a good unit, the sequence is the same except I see data on TDO first with the TMS pulses, and then I see a combination of TDO and TDI data. I have checked continuity on the TRST, TMS, TDI, TDO, and TCK lines and everything looks ok with the proper pull-ups and system power. I've built up the circuit about a dozen times and connected to the target successfully. Also, the chip seems active as the default watchdog timer overflow is firing. If there was a bad power supply input, I'd expect the chip reset (nXRS) to remain low in a POR or BOR condition.
Are there any other signals that would help diagnose what the problem is? The SDFlash error is "OTIS error, Error = -1135", but Spectrum Digital says these are legacy error codes and don't convey any useful information.
Thanks,
Louis
