Arduino Mini Pro 5v - how to power

[ddluk]

By mistake I bought some time ago 10pcs of Arduino Mini Pro 5v (instead of 3.3v) and now I've got a problem how to give them power? It's better to use:

• 2x1.5V AA batteries and use step up converter to get from 3.0v -> 5.0v

• 4x1.5V AA batteries and use step down converter to get from 6.0v -> 5v

Or maybe there is different possibility? I will be really happy if someone will be able to help me with this issue.

[Zeph]

You have two potential voltage inputs:

• 7v+ @ Vin to the input of the onboard linear regulator
• 5v @ VCC to the processor (and the output of the onboard regulator).

The 7v+ figure is approximate, it depends on the onboard regulator and the current draw, but the APM generally does not have a Low Dropout Regulator so it needs a couple of volts of drop.

You could use an external step down converter to drop 6V nominal to 5V for VCC pin - that could be a external low dropout regulator. There's not much point to a switching "buck" regulator - when dropping from 6V to 5V, the LDO linear regulator will probably be more efficient, cheaper, smaller, etc.

Or you could use a switching "boost" or up converting regulator from the nominal 3V source to 5V for the VCC pin. Either can work.

Either way, since you are going in through the VCC pin, you may want to unsolder the onboard linear regulator, to avoid it wasting power when fed from it's output.

[ddluk]

Thanks for information. So as I understand I can use those element - New 1-5V to 5V 500mA DC-DC Boost Converter Step Up Power Module (http://www.ebay.com/itm/390710998553) to convert 3.0v to 5.0v ?

[Damme]

@ddluk I run my 5v 16mhz at 3.3v.. Direcly off 2 AA batteries too (I think the reported voltage last I checked was 2.88v, Still works just fine. :) (But I have flashed bootloader to disable brownout voltage)

[ddluk]

@Damme

Could you tell me how to flash this bootloader? It will be nice to use those 5.0v with 2AA batteries :)

[marceltrapman]

@Damme said:
But I have flashed bootloader to disable brownout voltage

Interesting, are you saying that you removed the boot loader and use an external programmer or do you use another bootloader (I must admit that I did not pay attention too much when the bootloader was discussed elsewhere on the forum)?

[Zeph]

I think he's talking about setting fuses, rather than the bootloader per se - but it's often done with the same tool (eg: AVRDUDE).

The bootloader is code that runs in a protected portion of Flash memory. The fuses are a few extra bytes of low level processor configuration. Both are set using the same tools.

You can google for programming ATMega328 fuses (and look in the datasheet for the bit values).

[korttoma]

Anybody have any thoughts about running the Pro Mini 5v or 3.3v on one of these:

[marceltrapman]

@Zeph interesting stuff. Will look that up as soon as I am home again...

[hek]

I've added an ISP programmer (used to program Arduino bootloader) in the "shop" now.

[epierre]

@hek looks like you've ha enough of arduino slowdown you now propose a cubie ;-) A lipo would be a very good addition to the store too !

I'm searching for a leaf wetness sensor... not a rain sensor, hard to find as it seems...

[hek]

Cubie has a bit more processing power than RPi. For the demading controllers :)

@epierre said:

leaf wetness sensor

The only leaf wetness sensors I can find is super expensive. Like this:
http://www.ebay.com/itm/Brand-New-DAVIS-LEAF-WETNESS-SENSOR-/331222331582?pt=LH_DefaultDomain_0&hash=item4d1e63b0be

Can you (or someone else) recommend any lipo battery seller on ebay? I haven't got any buying experience just yet.

[epierre]

@hek yes it looks like I've added one sensor to much on the raspi... (infact 10...)

For the Lipo, no idea yet (not supercaps...), I was hoping this thread would propose something interresting...

For the leaf wetness I'll try with the rain sensor but... I need some autonomous energy system for it will sleep outside...

[Yveaux]

@hek @epierre What exactly is a 'leaf wetness sensor' and in what does your link differ from e.g. http://www.dx.com/p/cg05sz-063-rain-sensor-for-arduino-black-silver-works-with-official-arduino-boards-266534#.VAv7_FV_v7s ?

[hek]

@Yveaux

http://en.wikipedia.org/wiki/Leaf_wetness

Probably just a calibration/quality thing. The technique/principle is probably the same.

[Yveaux]

@hek OK thanks.
Reading this I think there also is a very close relation to humidity sensor readings. Would be nice to see the readings of both next to each other!

[epierre]

@Yveaux @hek I've forked to its own post: http://forum.mysensors.org/topic/352/leaf-wetness

I'll try to add things following mysearches and experiments

[epierre]

@hek

http://www.cooking-hacks.com/lipo-rider-pro
http://www.cooking-hacks.com/shop/arduino/converters/5v-regulator-module-for-arduino
http://www.cooking-hacks.com/7-4v-lipo-2200mah-battery-arduino-power-jack
they have the same at spark.io (hardware cum software like mysensors, same radio different core) :
http://docs.spark.io/shields/#battery-shield

The battery shield is a LiPo battery charger and voltage regulator combined into one. You can use it to power your Core with any 3.7V LiPo battery and charge it at the same time via the USB port. The shield is built around Microchip's MCP73871 battery charge management controller and TI's TPS61200 boost converter for up converting 3.7V to 5.0V.

There are plenty of 3.7V lipo batteries on ebay.com ...

[hek]

@epierre said:

http://docs.spark.io/shields/#battery-shield

Moustache shaped LiPo charger. Hmm.. ;)

The lipo-rider looks good, but there's mostly the older version on ebay. They seem to have switched JST-connector-version between their rider-revisions.

It is still hard to recommend LiPo batteries from ebay without doing some tests on them. I wouldn't use any without protection as they might explode if you use/charge them wrong.

[epierre]

@hek sadly I'm not expert at all on this to test them...