SimpleAtoD Example resets board when SW8 change

[seulater]

I am running V2.6 on the MOD5441x dev kit.
I loaded up the SimpleAtoD example. All dip switches are up (toward the module). When the app starts all is well. if you slide SW8 down the board resets. The rest do not do this. What is the work around ?

[dciliske]

I can confirm your issue on a MOD54415 rev 1.5, with processor revision 1M38W. I can also confirm that the issue is not present on rev 1.6 with processor revision 0N51E. This is related to Freescale errata SECF171.

The problem as listed in the errata:

ADC_IN7/DAC1_OUT pin has latch-up susceptibility at a low injection current level (40mA vs. 100mA spec). This is true for positive polarity injection at 125°C.

The workaround is:

Must prevent large injection currents with board level protection such as a series resistance.

I have also found that including external input for VDDA_DAC_ADC (i.e. V_aref) from V_cc and input VSSA_ADC/VSSA_DAC_ADC (i.e. V_agnd) from V_gnd alleviates the issue.

[Edit: Just for perpetuity, this was a pre-production board that got sent to a few early beta testers. We have shipped any production boards with the rev 1M38W processor.]