Experimenting with low power modes and Arduino


Image

Tero Koskinen recently did interesting experiments exploring how low power he can go with Arduino. http://arduino.ada-language.com/saving-power-with-avr-ada.html

He made setup with 5 boards to test:

  • original Arduino Duemilanove
  • original Arduino UNO
  • Olimexino-328 clone
  • Arduino DIY PTH kit from Sparkfun
  • Diavolino from Evil Mad Scientist

He correctly shut down all not used peripherials, Brown-Out-Detection, slowed down the CPU speed and used Power Saving modes.

the results were:

Device Current
Duemilanove 7.50mA
UNOr3 18.10mA
Olimexino-328 4.00mA
Sparkfun PTH Kit 7.60mA
Diavolino 0.50mA

 

Diavolino have nothing but the AVR so obviously is winner with this setup with only 0.5mA consumption.

Wait if there is no power regulator where these 0.5mA go when AVR is put in low power mode?

Looking at the schematic  you can see R1 RESET pullup 10K resistor which is connected to 5V -> 5V/10K = 0.5mA the whole consumption is taken by R1!!!

 

Then let’s see OLIMEXINO-328 the second place with 4mA (outch!) this board is promoted by OLIMEX as SUPER DUPER LOW POWER BOARD then why these bad results? Where these  4mA go?

The answer is obvious: Tero is powering OLIMEXINO-328 by the POWER JACK.

In our design we assume if the power come from the power jack it’s unlimited and we can waste it as much as we need – charging Lipo (if attached) etc.

So these 4mA are taken from the DCDC in the input.

If Tero wanted to see how OLIMEXINO-328 shines in low power he should have powered the board by the battery connector. When the power is applied to battery OLIMEXINO-328 is very humble and will need less 20 micro ampers 0.02 mA to operate!

How this is done? If we look at the schematic we will see that there is no RESET pull-up, but the RESET is done by tricky circuit with R12/R13/SD5/C7/C8 this schematic have zero consumption but still perform RESET functionality.

Also unltra-low-power LDO which needs just 3 micro amps to operate MCP1700T-3302E/MB is used for power regulator.

This makes possible complete Arduino to may keep working while consuming less 20 micro amps.

What 20 micro amps consumption means? If you use our standard LiPo 1400 mAh battery your board can work 70 000 hours or 3 years!

The other boards: Sparkfun kit 7.6 mA, Duemilanove 7.5mA and UNO 18.1 mA just use cheap voltage regulators which take this current, but it’s OK they have not been designed to be low power.

What is the conclusion: with right setup (powering from battery) OLIMEXINO-328 is the lowest power Arduino solution on the market! When we add to the low power the industrial temperature operation range -25+85C and the possibility to work with any input voltages from 9 to 30VDC, OLIMEXINO-328 is the most sophisticated board with many features while keeping the price reasonable.

2 Comments (+add yours?)

  1. Ivan
    Nov 05, 2013 @ 23:02:17

    well guys, you should report that to Tero

    Reply

  2. Tero Koskinen
    Nov 06, 2013 @ 02:32:49

    Thanks (I noticed your Twitter messages earlier, but took some time to verify the results).

    You were correct hat the Olimexino-328 power usage can be much lower than 4mA.

    I was first using power save mode, which others have also reported to be using quite lot of power (1.6mA at http://www.gammon.com.au/forum/?id=11497 ).

    I changed my code to use power down mode + watchdog for wakeups and managed to get power usage with Olimexino-328 down to 0.02mA. I also noticed that INA219 sensor resolution stops at 0.1mA, so had to switch to multimeter (I have one which should support measurements down to 0.01mA).

    Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: