I am sure you have tried more than one part.
You mentioned UART, is RS232 link connected directly to PSOC or are you
using a RS232 level translator, like MAX232, to supply LV signals to/from PSOC ?
If former you might be damaging PSOCs, bit not the whole chip, generating erratic
behaviour.
Another possibility is a GPIO pin with an aperiodic transient on it. Use a DSO,
set it to trigger on VDD + .7 or VSS - .7, single shot, see if you can capture a
signal that violates datasheet specs. Suspect any high L loads, like relays,
motor, etcc.. generating ground bounce or coupling into hi z pins.
Use DSO on infinite persistance, look at supply pins, to see what PK-PK noise
is present in system.
Regards, Dana.
