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Topic: OK, Nano..... how low can you go? (Or.... "Can Atmel limbo"? (Read 562 times) previous topic - next topic

TroyO

The specs on the Nano says that it takes 6-20v.

Bypassing the Vreg and supplying your own 5V, you can get down to 5v

4x Nimh Batts are ~4.8V...... close enough? How about 1X Li-Ion cell at 3.7V?

I am trying to design a simple shield that will be battery powered and would love to not have to build in a boost converter if I can get away with it. I've been reading the datasheet and the charts aren't exactly high precision... LOL.

It lists 2.7v as "safe" to 10 Mhz, and 4.5v as safe to 20 Mhz......  10 Mhz over 1.8v...  0r .18v/Mhz. 10 Mhz @ 2.7v plus .18v x 6 Mhz... 3.78v as a bottom end safe voltage @16 Mhz? (It's probably not exactly linear.... but it's something to guess on...)

My take.... 4.8v is just fine..... 3.7v is really pushing it. Dang it, so close yet so far... LOL.

Does anyone have real world experience? I'm hoping that the "Safe operating voltage" means it may cough and screw up once in a blue moon but will basically be just fine.


dhenry

Quote
Does anyone have real world experience?


I have ran those chips safely from 2.5v to 7v.

TroyO


Quote
Does anyone have real world experience?


I have ran those chips safely from 2.5v to 7v.



@ 16 Mhz or did you have to drop to 8Mhz at the lowest V?

dhenry

8Mhz internal.

I don't think you will have much trouble pushing it beyond the datasheet. Just experiment.

TroyO

True that.... handfull of chips and a custom board or two and even if it fails utterly I'll learn a lot.


retrolefty

Quote
How about 1X Li-Ion cell at 3.7V?


Keep in mind that is a nominal cell voltage, the actual voltage ramps down from 4.2 at full charge down to 3.0 where most people stop or risk damage from over discharge.

Why fool around, just use a very small and inexpensive switching regulator module:


http://www.ebay.com/itm/DC-DC-5V-1-5A-Volt-Voltage-Regulator-Convert-Step-up-USB-Power-Module-IN-1-5V-/270875152616?pt=LH_DefaultDomain_0&hash=item3f116ad0e8

http://www.ebay.com/itm/3V-to-5V-500mA-Mini-DC-to-DC-Converter-Boost-Power-Voltage-Input-Step-Up-Module-/280911456875?pt=LH_DefaultDomain_0&hash=item4167a0aa6b

Lefty

TroyO

I'm designing a board intended to be a lightsaber "shield" for the Arduino nano, (.7" x 2.25" Hopefully) which will house a microSD card, accelerometer, audio amp and 1.X amp PWM controllable LED driver.

People regularly choose 1x L-ion, 2x Li-ion or 4x NimH batteries. (They most readily fit inside a lightsaber "hilt".)
I would (and will) include a switching regulator if space allows but the board is small.

It may be better/easier to indicate they need a step down for 2x Li-Ion, a step up for 1X and are probably OK with 4x NimH. As you point out they are easy/cheap on Ebay and you can customize it to fit the need.

Anyway, the idea is using off-the shelf components and with freely available files (Eagle, gerbers, code, etc) so anyone can build thier own or modify it, etc. While there are commercial options out there none are fully programmable like the Arduino which I think will appeal to some designers. In my case, I want a full color lightsaber and nothing else controlls RGB, LOL. (The WIIFM... ;-)


MichaelMeissner

#8
Jan 04, 2013, 10:27 pm Last Edit: Jan 04, 2013, 10:43 pm by MichaelMeissner Reason: 1
Besides the Nano, another possibility might be the TinyDuino or TinyLily: http://tiny-circuits.com/products/tinyduino/.  They aren't shipping yet, but soon will be.

Teensy 2.0/2.0++ boards might also be a possibility: http://www.pjrc.com/store/teensy.html and http://www.pjrc.com/store/teensypp.html.

In terms of battery for your light saber, I was looking for accessories for my new Samsung Galaxy S-II cell phone, and I noticed this battery on ebay: http://www.ebay.com/itm/330772818549?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649.  Unlike most of the batteries I've seen, it is only 22mm (0.87") in width, which might work well in a light saber handle.  The power is 1850 maH.  For a comparison, I ran my normal Arduino Uno with a 5000 maH battery doing blink, so it should give you about a day at a convention before you have to recharge.

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