SBL2E locks up and need power cycle to resume working

[Ranba790]

Hi
We are using SBL2E with the latest version(1.65). We use one serial port and the rest as GPIO.
The units runs OK, but every couple of days the unit locks up, doesn't even respond to a ping. We have 5 units and all act the same.
Recycling the power to the unit solve the problem and it will run again for couple of days.
I may have something to do with 3.3V supplying going low, not all the way to 0V but going like to 3V or lower and from that the unit doesn't recover.
Any idea how to solve it. Is there a watch dog i can enable or brown-out protection
Thanks

[rnixon]

If your dropping below the min. voltage the on-chip watchdog might not work either. Is there some way you can do a test and keep one unit at the specified voltage to verify the problem goes away? How about adding an external watchdog with a wider voltage range so that it can pull the SBL2e reset pin low? Of course you would need to verify a soft reset can reset the processor after the brown-out condition (maybe a power cycle is required).

Why is the voltage going changing so much?

[Ranba790]

Thanks for the reset suggestion
Do you know what is recommendation for the reset pin connection, Right now i don't have it connected(its open).
Thanks