71B MultiMod: MEMORY LOST when changing batteries?

[mfleming]

Very interesting playing around with the J2 jumper and battery replacement process. With the J2 jumper out, I didn't see a Memory Lost condition when turning the 71B on and off. So, I next tried simulating battery replacement with and without the J2 jumper in place.

With J2 in and the processor asleep, I lifted one battery at a time, counted to three, reseated the battery and counted to three again before lifting the next. No Memory Lost condition, and this matches the way I normally replace batteries (I probably fumble a little longer between battery pulls in real life).

With J2 out however, I get a Memory Lost repeating the same steps above, whether the 71B was just turned off or whether I waited several minutes for the processor to go into deep sleep before disconnecting power. So, counterintuitively, it's better to leave the jumper in when changing batteries.

I've yet to lose memory changing batteries this way, but that's not to say you won't. As Sylvain notes, it's better to have the adapter connected. Meanwhile, I'll look into forcing the processor into sleep mode after power-on reset, and only allow Daisy-In to wake the processor. That could conserve charge to power the rest of the 71B during battery replacement.

~Mark