Miniature stepup - will it work with a nano?
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I am trying to make my sensors smaller and less clattered. currently the worse mess is the battery->stepup->nano, as step-up to nano is a usb to miniusb cable which is awkward. I found these http://www.aliexpress.com/item/2-pieces-lot-mini-dc-dc-converter-0-9-5V-to-5V-DC-DC-step/32268732761.html and was thinking to use them instead and solder the output to the vin and ground. I guess i can just try but would appreciate knowing before ordering if this will work or if these stepups are known to consume batteries or whatever.
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@Moshe-Livne According to spec it should work. But why aren't you moving to the smaller micro arduino boards if you want to save space? these need less power and much smaller. Or Senseender micro?
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@AWI i will but i have a stock of nanos. Just ordered some mini pros and ftdi writer. This is all new to me so i am making all the mistakes by the book....
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@Moshe-Livne Great that's what I love about this renewed hobby too. Being able to make a lot of mistakes
Nanos are great as they have a built in USB serial port and double voltage. Downside is that they are not the best for battery operation (unless you also have a large stock of batteries 
)
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I have the 3.3v version of that step-up, and it works pretty well with a pro-mini 8MHz / 3.3v board. That's probably what you want if you are looking to run off of batteries, though 5v shouldn't be that much more of a mA hog if you're only looking to run for a couple of months at a time. For years you definitely will need the lower voltage (plus mods... search other threads for details).
Some anecdotal observations from the step-ups I have:
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I think that these will run your batteries into the ground if you aren't careful. As far as I can tell there is no cutoff circuitry. So not sure if that will kill expensive rechargeable batteries....
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On the pro-mini form factor, as long as you make sure A2 and A3 are INPUT (the default) you can plug this adapter in directly to (A2, A3, VCC) <-> (Vin, GND, Vout), then jumper from A3<->GND. This means less wiring on a breadboard / soldering on the board, and as an added bonus you can monitor the battery level with a simple analogRead(2). (Just be aware that NiMH batteries have a non-linear voltage curve, so as soon as they drop below 1.2V per cell you're nearly out of gas...)
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Erm... scratch what I said about making sure A2 and A3 are inputs; I'm pretty sure that analog pins on Arduino pro-minis can ONLY be inputs. There's no DAC hardware on the chip. (
analogWrite()uses PWM on digital pins.)
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@rickmontana83 Thanks! i'll order some. As I said, I have a stash or nanos... but its a silly reason, i know. the cost of the nanos is almost like the cost of a pair of batteries. Just got my first batch of minis but ftdi is still swimming from china... as they say, patience come to those who wait. as for your number two, can you elaborate? I thought you connect the output of these to Vin and GND or something (still didn't look at the mini so i might be mixing things with the nanos)
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The "trick" here is that I wanted to keep things as tidy as possible on a breadboard, and didn't want "dangling" components or use up extra pins (I'm trying to mount everything on a mini breadboard, and have no space to waste). So the problem becomes finding a set of three side by side pins on the mini that won't hurt anything when I plug in the adapter.
It would all work out fine if RAW-GND-VCC sat next to one another, but they don't. So I used two analog pins that won't be hurt by Vin or GND from the adapter, and Vout from the adapter falls on the VCC pin. Jumper from A3 to GND to connect that up and voila: adapter sits right alongside the arduino, and I can monitor the raw battery voltage on A2. Only A3 gets wasted, and I typically don't use that many analog pins anyway.
Next round I think I'll optimize breadboard space by only soldering a subset of the male pin headers on the arduino, and providing upward facing female headers. Hat gives me move free space on the breadboard, while still allowing access to the arduino pins.
Of course, all of this is a little crazy, since I should just prototype on a big breadboard and then finalize on a proper circuit for the battery pack, but it's really fun to have reconfigurable battery pack units...
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ummmm forgive my ignorace but why do you have to connect to both vin and vcc? i thought only two connections are required, vin and gnd? but yes, if it goes leg for leg its much neater.....
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@rickmontana83 Ummmm a question (after making my battery powered sensors). Why do you need these at all? won't the constant draw of voltage defeat the saving in draining the battery? and won't the internal regulator take care of this as well?
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@Moshe-Livne said:
ummmm forgive my ignorace but why do you have to connect to both vin and vcc? i thought only two connections are required, vin and gnd? but yes, if it goes leg for leg its much neater.....
The board in the link has three pins: Vi (voltage in), GND and Vo (voltage out).
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@blacey oh i see. My pro mini has vin written on the raw pin so i mixed it up. Thanks!
