Using the prop 1 for measuring then logging current draw of various domestic clothes washers and dryers. I've evolved a configuration that uses an op amp to amplify the output of a 200:1 current transformer. The op amps output is adjusted by a digital potentiometer communicated to by I2C which then gives a calculable level. Only need a rough reading so an ADC would be overkill.
The circuit works perfectly as designed except for one fatal flaw. On just some machines the prop very sporadically reboots loosing all data before it can be stored to persistent memory. I've tried valiantly to replicate the problem in the lab so I can analyze it but could not.
I've got BOE hooked to ground. A 1K resistor to VSS and a 1uF cap to ground on the RES pin. Also the trace to the reset pin is very short and nothing is hooked to it during operation. Using a stand alone packaged power supply (RAC02-05SGA) simply because I couldn't build a custom one for less.
There are two PCBs in the device aprox 20 centimeters apart with a 4c#22 cable interface. The power supply, CT and some 5V relays (not active during operation) are on one. The main controller with the prop has everything else on it, including a 3.3V regulator (MIC5504-3.3YM5-TR) and a 16x2 LCD.
So I'm pretty sure this problem would have something to do with the fact that the power supply is fed from the same AC line that feeds the appliance where heavy loads are turned on and off during the cycle but I'm not certain.
Would anyone here know how to reliably power the prop from such a noisy AC source?