Author Topic: strange behavior after removing Moteino's voltage regulator  (Read 1264 times)

WhiteHare

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strange behavior after removing Moteino's voltage regulator
« on: February 19, 2016, 05:16:31 AM »
I removed the voltage regulator on a couple moteino's (I also connected Vin to Vout between the Moteino's voltage regulator solder pads), and now both of them exhibit the same strange behavior.  Basically, both work fine if I power them from Felix's FTDI connector (set for 3.3v).  However, if I power them by battery, then very often it will either freeze or reboot as a consequence of initializing the flash memory.  If I don't use flash memory, they seem to work fine.

Looking at the Moteino R4 schematic, it does look like there are some capacitors used with the voltage regulator when it was there: 1 0.1uF, a 10uF, and a 1uF capacitor (  https://github.com/LowPowerLab/Moteino/blob/master/R4/MoteinoR4_schematic.pdf)  Should I remove them as well now that I've removed the voltage regulator?  I'd like to be able to run a Moteino directly from a 3v battery source (two AA's in series).

Has anyone else run into this?
« Last Edit: February 19, 2016, 11:03:26 AM by WhiteHare »

jra

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Re: strange behavior after removing Moteino's voltage regulator
« Reply #1 on: February 19, 2016, 10:05:16 AM »
Haven't tried it.  How much voltage are your two AA's actually putting out?  Running an ATMega328 at 16MHz on 3v3 is slightly out of spec, reducing it to 3V moves it further out of spec.

WhiteHare

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Re: strange behavior after removing Moteino's voltage regulator
« Reply #2 on: February 19, 2016, 12:08:42 PM »
Good point.  To test that theory, I just now hooked it up to a 3.3v bench power supply, and it's exhibiting the same behavior as with the two fresh AA batteries at 3v.  I even kicked it up to 3.4v and 3.5v to see if that might help, but nope.

Yet, if I connect it to Felix's FTDI friend (set at 3.3v), it works just fine.   :o

WhiteHare

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Re: strange behavior after removing Moteino's voltage regulator
« Reply #3 on: February 19, 2016, 01:02:40 PM »
I just remembered that I have to wire DTR to GND to get Flash memory to work.  Did that, and now it works fine on the two AA batteries.   :)