Other Parts Discussed in Thread: MSP-FET
Tool/software: Code Composer Studio
Have used this part in several previous designs, However, I am experiencing an unusual and disturbing issue with my current design. P5.1 and P5.2 are being used to communicate over an SMBus implementation driven by a software/firmware block of code, not any internal hardware resources. These two pins connect to a spring connector on the edge of the card and attached by right angle screw connectors that provide power and Ground. The card generates +3.3 Vdc using a switching regulator that will run off 6 to 40 Vdc. The port pins have protection diodes tied to +3.3 Vdc and Ground. The oscilloscope measurements show a few hundred millivolts of undershoot and overshoot when this daughter card is connected to its Base Card. The maximum length of the Base Card is slightly over 12" in length and has no circuitry other than traces connecting the daughter cards together. The SMBus 10K pull-ups are on this card for test purposes.
The problem I am having is after days of testing with various other daughter cards the port pins stop working correctly and can no longer program the part. The last card I tested with this issue will not program or allow debugging but appears to work as desired if the JTAG connector to the MSP-FET Flash Emulation Tool is removed. Changing FETs makes no difference. This card may work for a day or a week, sometimes longer. When the problem occurs I observe slightly distorted triangular spikes that are 1 to 6 ms wide and spaced about 10 ms apart, at least with the current card under test. Previous cards exhibited similar results or stopped working altogether. I should have documented these cards more thoroughly but there were other hardware issues that could explain the failure of these port pins. However, the other daughter cards have been thoroughly tested and modified to eliminate any known issues and in recent weeks only firmware development has been the focus.
I have pictures, videos, schematics, and software/firmware listings I can provide if needed
Your assistance in this matter would be greatly appreciated.
Regards, Harvey Novak