Low Power: How much current? [Solved]

NeverDie

@5546dug @NeverDie One thing to be cautious of is that not all Mini's use the same board configuration so the instructions may need to be altered depending on exactly with Mini you have.

Cheers
Al

At the moment I'm wondering whether different Pro Mini's might consume more power than others, even if setup the same. I followed the author's directions, but I'm getting 17uA of current in power-down sleep mode (forever), not the 4.5uA that the author claims to have measured on his. Maybe it has to do with the configuration differences you're referring to? Or, I suppose it could be measurement error (either mine or the author's or both). I'm using a uCurrent Gold in conjunction with a Fluke 87V to do my measurements. The author didn't say how he did his, so I sent him an email asking for the details of how he measured.

I am pleased though at having gotten such a gigantic reduction by following such a simple 3 step process.

sundberg84

@NeverDie Experience the same... even though I have same boards/same batch and same actions to reduce power they are difference in how fast they drain battery.

NeverDie

@sundberg84 said:

@NeverDie Experience the same... even though I have same boards/same batch and same actions to reduce power they are difference in how fast they drain battery.

What magnitude of variation are you noticing? e.g. what are the high and low numbers?

sundberg84

@NeverDie Sorry i dont have the equipment for numbers... Only some run out of batteries in 3 month and some last for... A very long time.

NeverDie

I have a hunch as to what's causing my higher current drain. I took a more careful look at the author's photo, and it looks as though he didn't solder evem a single wire to the board. Rather, it appears he connected Vcc and Ground through probe clips or something.

In my case, I soldered on 30 header pins, and so my hunch is that the residual solder flux is causing a current drain that may account for much of the difference between the author's measurements and mine.

I'll try the author's three steps again on a new Pro Mini board, equivalent to the first, but this time I won't solder on any header pins.

NeverDie

@NeverDie said:

I have a hunch as to what's causing my higher current drain. I took a more careful look at the author's photo, and it looks as though he didn't solder evem a single wire to the board. Rather, it appears he connected Vcc and Ground through probe clips or something.

In my case, I soldered on 30 header pins, and so my hunch is that the residual solder flux is causing a current drain that may account for much of the difference between the author's measurements and mine.

I'll try the author's three steps again on a new Pro Mini board, equivalent to the first, but this time I won't solder on any header pins.

Apparently not. I couldn't find another Pro Mini board of the same design, so I tried one with a different design, but this time I didn't solder anything. I followed the same steps as before, and I got the very same 17.2uA as I got before with the Pro Mini that I soldered 30 header pins on.

So, same current measured on different boards, but connected differently. Unless someone has an alternate theory, it seems to me like that maybe really is the current.

Anyone else tried it and measured it? The three steps take less than 5 minutes. You just remove two components (or remove one component and cut a trace to the other) and upload a "deep sleep forever" script and then you're ready to take measurements.

scalz

@Neverdie: I am not at home today. But I remember that I had difference using lowpowerlab lib. Very strange. So I started to write my own function.
One trick to check if you want: test sketch J from http://www.gammon.com.au/forum/?id=11497
I had better result with it.

brolly759

OK I am going to join the party as this is exactly what I have been testing this past week. I have a uCurrent Gold and running on an 8Mhz 3.3v Nano Pro from this site:

https://www.sparkfun.com/products/11114

I have un-soldered the smt jumper to bypass all voltage regulating and running off of 2 AA Batteries.

I am using the BinarySwitchSleepSensor sketch from the MySensors library. This uses pin 2/3 as an interrupt and sleeps until a pin hits GND. It wakes up, sends the new state, and goes back to sleep. The sketch also makes pin 2/3 high and uses the internal pull-up resistor.

Originally I was getting 23-24uA in sleep mode when GND was not connected to pin 2/3. 117uA when GND was connected to pin 2/3. We will refer to this as open and closed pin state.

Here is my methods:
I downgraded my version of Arduino IDE to 1.0.6 from the latest build 1.6.5 and here are my new numbers:

2.5-2.7uA sleep mode - Open pin state
98-100uA sleep mode - Closed pin state

Then I deleted from the sketch the digitalWrite on pin 2/3 and used an external resistor thanks to the advice from AWI. I plugged in an 10M Resistor to pin 2 to VCC and GND was the switch. Here are my new numbers:

2.5-2.7uA sleep mode - Open pin state
3.1-3.2uA sleep mode - Closed pin state

So far today I have not gotten any false positives in my setup which is freaking amazing.

Now I used a quick sketch "DallasTemperatureSensor" from the MySensors library to test what my current would be in sleep mode with a watchdog timer. I did NOT connect a temp sensor but my sleep current is: 7.6uA - 7.8uA.

I hope this helps and if you need any testing let me know.

I have a post on the Arduino forums here:
http://forum.arduino.cc/index.php?topic=341958.msg2360300#msg2360300

You can see me talking to the guy who actually wrote up the gammon website and you can ask him things directly if you ever wanted too. Very helpful guy!

NeverDie

Thanks! Very timely, as I was just now hunting for a 3.3v 8Mhz Pro Mini that might work.

Sparkman is right. Now that I'm looking more closely, I'm finding that there are a lot of "configurations" of the pro mini. Amazon is selling some (possibly fake) Sparkfun pro mini's that superficially resemble the one brolly759 has, except they're missing the solder jumper, and some of the passives look smaller.

http://www.amazon.com/gp/product/B00JNYXC8Q/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A1LHQ5G6ONPXVT

http://www.amazon.com/gp/product/B00Q9YAP2E/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A34K5WF5Z9R33P

I'm in a bit of a hurry because I don't want to lose momentum, so I'll be the guinea pig and order the red ones. If they don't measure out well, then I'll order one direct from Sparkfun.

Ultimately, though, I'd like to find a source for a truly low power "configuration" at closer to the $2 from China. If that's not possible, then before giving up I want to at least understand why it's not possible.

brolly759

I think at one time, the pro mini did not have the power jumper and china copies the boards and resells them. They probably never refreshed the product line. Here is an article in 2013 of someone trying to do low power on the boards that you are referring too:

link text

Here is the trace you need to cut to bypass all the voltage regulation crap:
link text

If you have one of the cheap boards, I would cut the PCB trace first and retest before buying new stuff. Let me know what happens.

scalz

@Neverdie: during my low power tests, I have used these http://s.click.aliexpress.com/e/feUvNFufi and it worked like I said. Arduino pro mini, I think you know it, is basically an atmel with some components. And I think most of arduino clones follow Arduino reference schematics. Just rooting and placements is different. So, in theory, it should work. but maybe bad components like capa, and I am not sure, could be the cause. but, in this case, it means that you can't be sure with all clones too and you need to find the good supplier. very strange and not cool. or maybe could it be counterfeil atmel...I don't think.
Did you tried Sketch J from Gammon. Do you have still the problem??
And of course like Brolly said, I removed voltage reg stuff.

brolly759

Dont forget to check the Atmega chip. There is Atmega328 and 328P versions. You need the "P" As that is designed to be power efficient.

Here is some more info on that:
link text

NeverDie

@scalz said:

@Neverdie: ...and it worked like I said.

@scalz To avoid confusion, I'm feeling the need for clarification: Do you mean that particular pro mini, from that particular vendor, is what you succeeded in bringing down (by unspecified means) to below 1uA sleep current?

scalz

yep. funny you proposed this link, and I checked on my ali orders and it is the same!
what do you mean by "unspecified means". I am not sure....

NeverDie

@scalz said:

yep. funny you proposed this link, and I checked on my ali orders and it is the same!
what do you mean by "unspecified means". I am not sure....

By "unspecified means", I just mean that you never said how you managed to do it. Rather, you said you'd rather let Charles say how he did it, whenever it is that he feels like he's ready to say.

So, apparently, I was confused. For some reason I thought you had managed to achieve <1uA sleep current in an entirely custom way and that the Pro Mini's from Great Wall Electronics were unrelated to that. That's why when I stumbled across the 3-step article I posted earlier in this thread, I thought I'd just press ahead with that because it made the entire process (seemingly) so simple. Well, it is simple, except all the different "configurations" muddied the water and created doubt about what sleep current I might really get, maybe even depending on which "configuration" I got.

At this point I'd be happy with 3.5uA. Based on the above, it sounds like Brolly759 found a way to reduce sleep currents down even further to 2.5-2.7uA, though I haven't yet wrapped my head around how Brolly759 did it, aside from reverting to IDE 1.0.6. I need to back up and re-read what he wrote now.

scalz

@Neverdie: ok. this is what I was thinking..ahah no problem. I think you have misunderstood me.

First, I think Brolly knows how to get low power as he said he has studied Gammon sketch. have you?

Then, at the beginning I give you links to achieve low power but you told me that you wanted an easy to do way (the link with coin cell) and told !scalz. So I thought you didn't want to know more.

So, if you want to try these steps and check (this was my first steps):

arduino pro mini, remove led and voltage reg
upload sketch J from Gammon, so you will be sure the best you can achieve
check at your uCurrent you will be < uA
Mysensors part : make a function from this sketch J and use it for sleeping instead of gw.sleep which use lowpowerlab (very strange I had difference with it and didn't investigated more). but you will need to find something for your radio next...like mosfet but it is other things.

But If you try it, you will see with your eyes now...

Yes I have already some codes. but I told you I don't share as it is experimental, not clean, and a good lib will be released soon. So i don't want to spend more time for nothing.

NeverDie

@brolly759 said:

OK I am going to join the party as this is exactly what I have been testing this past week. I have a uCurrent Gold and running on an 8Mhz 3.3v Nano Pro from this site:

https://www.sparkfun.com/products/11114

I have un-soldered the smt jumper to bypass all voltage regulating and running off of 2 AA Batteries.

I am using the BinarySwitchSleepSensor sketch from the MySensors library. This uses pin 2/3 as an interrupt and sleeps until a pin hits GND. It wakes up, sends the new state, and goes back to sleep. The sketch also makes pin 2/3 high and uses the internal pull-up resistor.

Originally I was getting 23-24uA in sleep mode when GND was not connected to pin 2/3. 117uA when GND was connected to pin 2/3. We will refer to this as open and closed pin state.

Here is my methods:
I downgraded my version of Arduino IDE to 1.0.6 from the latest build 1.6.5 and here are my new numbers:

2.5-2.7uA sleep mode - Open pin state
98-100uA sleep mode - Closed pin state

Then I deleted from the sketch the digitalWrite on pin 2/3 and used an external resistor thanks to the advice from AWI. I plugged in an 10M Resistor to pin 2 to VCC and GND was the switch. Here are my new numbers:

2.5-2.7uA sleep mode - Open pin state
3.1-3.2uA sleep mode - Closed pin state

So far today I have not gotten any false positives in my setup which is freaking amazing.

Now I used a quick sketch "DallasTemperatureSensor" from the MySensors library to test what my current would be in sleep mode with a watchdog timer. I did NOT connect a temp sensor but my sleep current is: 7.6uA - 7.8uA.

I hope this helps and if you need any testing let me know.

I have a post on the Arduino forums here:
http://forum.arduino.cc/index.php?topic=341958.msg2360300#msg2360300

You can see me talking to the guy who actually wrote up the gammon website and you can ask him things directly if you ever wanted too. Very helpful guy!

If you removed your switch from the equation and just had the arduino pro mini sleep and never wake up (yeah, I know, it's a NOP), what sleep current would you get? That's the sleep current I've lately been trying to measure, because it's the simplest, base case, and you can add current drains to that, as needed.

brolly759

This is testing using the Binary Switch Sleep sketch.

The switch is not active when its in its "open state" so there is no drain. I removed the resistor though and all the jumpes, I am still getting around 2.7-2.8uA is sleep mode without switch.

In sleep mode with the NRF ONLY VCC unplugged I am getting 1.3uA - 1.5uA.

In sleep mode with ALL cables unplugged from NRF I am getting a strange reading and not really sure which one is accurate but here are my numbers:
With uCurrent in uA mode I am getting .4uA -.5uA
With uCurrent in nA mode I am getting 110-120nA

I checked on Gammon site using the reference code, the nA of 110-120nA is accurate and the uA mode is wrong when I go down that low. So in short, I am getting 110-120nA when nRF is unplugged completely.

NeverDie

@scalz said:

I think you have misunderstood me.

Sounds that way. Probably my fault, due to lack of sleep.

check at your uCurrent you will be < uA

Excellent!

Next step for me: placing an order with Great Wall Electronics for 10x pro mini's, as that is now critical path. By the time it arrives (hopefully even sooner), l should have this figured out.

NeverDie

BTW, while on Great Wall, I noticed these RTC functional knock-offs of the Chronodot are just $0.57/each.

http://www.aliexpress.com/item/DS3231-AT24C32-IIC-Module-Precision-Clock-Module-DS3231SN-for-Arduino-Memory-module-Free-Shipping/32346088222.html

It might make sense to use one of them to wake up an arduino just once, when it needs to be woken, instead of every 8 seconds, as when using the Watchdog Timer. The current consumed by a genuine ChronoDot is: 200uA (active), 840nA (timekeeping) I don't have amp figures for the Great Wall knock-offs. I have a couple of the genuine chronodots, and they keep pretty accurate time.

Low Power: How much current? [Solved]

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