Electronics > Beginners
Bit of a noob, needing project assistance.
starhawk:
My computer is fine. I was powering the Nano off of a USB lead when I programmed it.
The regulator (indeed an A1117) on the SD card board is putting out 4.03v. That's a little high, IMO, but do you think it's within allowable tolerances?
EDIT EDIT EDIT: The A1117 on the SD card board was measured at no-load levels. I *could* power the board from the 3.3v lead on the spare Nano once I bodge that in -- *but* I absolutely cannot exceed 25mA current draw. Anyone know the typical draw of an SD card? Full size, not Mini or Micro...
Ian.M:
Nope. 3.5V would be an absolute upper limit for what's acceptable out of a 3.3V regulator. Connect a 330R resistor between its output and Gnd to load it with 10mA, and check its outputting between 3.2V and 3.4V. I'd bet it will fail that check as well.
IMHO its FUBARed, and you will need to either replace it or remove it and feed the SD interface 3.3V from an external source. I'd be very suspicious of a Nano's 3.3V pin being able to supply enough current for a SD card as its drawn from the USB interface IC, not a separate 3.3V regulator like a Uno has.
starhawk:
Hmmm... I have a 3v3 regulator that I stuck... somewhere... from one of many projects that never happened... it's a switching replacement for a 7803. Let me see if I can put my paws on it.
starhawk:
Found the regulator, and the replacement Nano took its programming with absolutely zero trouble. I didn't even have to hit the reset button this time to get it to listen!
I'm gonna see if I can't go ahead and put this thing back together. So far everything's coming up Starhawk (to borrow a catchphrase) -- but my luck usually holds together like dry snow in a kid's glove, so we'll see... I'll let ya'll all know how it works out once I've (re)wired and (re)tested it all.
Ian.M:
Do check the I/O pins you need for the project on the replacement Nano before you put it all back together. Time spent confirming there was no significant ESD damage while it was knocking about on your desk will save you a lot of time and much head-scratching and swearing if you have any problems with the completed assembly.
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