Some power benchmarks

-
After some time willing to do this I've found a moment to do some measurements. Firstly, I've removed Arduino Mini Pro power led resistor to see how much current was needed for the device in power-down mode: It's just 155uA@3V3, even lower if you go down to just 3Volts. The Mini needed 5mA for normal operation (with no output loaded).

The other component I was interested on testing together was Digi's XBee module. While XBee needs 50mA on operation, using SM=1 (Hibernate mode) the power goes down to 1.6uA when sleep mode is forced (by raising pin 9 to high).

That all means that a basic wireless sensor node based on this components will use at least 55mA during ON periods and 0.16mA while SLEEP. That translates into about 4 hours of continuous operation from a 220mAh 3V button cell.

However, if node is powered up only 3 seconds every 5 minutes, then the same battery should last around 13 days. This seems to start looking ok for my sensor network project.

Comments

Anonymous said…
Thanks, very interesting! I linked this entry to my blog, wsnblog.com.

Best,
Marco
1:51 pm
misan said…
I'm glad to be useful. Thanks for linking it.

Cheers,

Miguel
4:36 pm
Gustavo said…
Hola Miguel, gracias por tu aporte es un buen punto de comparación para comenzar otro proyectos.
1:11 pm
misan said…
De nada, Gustavo.
1:40 pm
Anonymous said…
Im not quite convinced that button cell battery can give 50 mA for XBee module. Try test with battery instead of power supply, and record (with scope) voltage of battery when it's heavy loaded (50 mA is much for coin battery).
For project I designed my own Sensor node (yes, it's silly, I know), and it runs on LiSO2 battery (3.6 V, 2200 mAh) with 4 uA sleep current and 30 mA active current. With 1 wake-up in 15 minutes (nodes are time synchronized) it can run for 10 years.
7:23 pm
misan said…
Hi Andro,

Neither do I. But I guess that's why capacitors are for :-)

Could you please provide a link to your work? (it's definitely not silly).

I still need to find the time to put it all together and do some real test. As far as I know, 400uA is the "recommended" discharge currentfor CR2032 button cells. I'm afraid too that 100 times that may be too much.
7:39 pm
Anonymous said…
Unfortunately, there is no web page of out Sensor node (I focused mainly on hw and node sw development). It was project on university where I worked with colaboration with industrial partner. You can find some material on web page www.maslinet and on http://aig.zesoi.fer.hr/archive.html.

Regarding capacitor use, be aware that larger capacitor (and, for these use you will probably need > 1mF capacitor) have significant (few uA, for this use) leakage current.
10:17 am
johannes said…
First of thanks for sharing
I'm making a automated watering system with soil humidity sensor, relay board, 2 18650 2500mAh Li-ion cells and 5V mini pro (putting my uno on the shelf since there is only a small difference between delay and pwr_down in power consumtion).
I was wondering if you passed through vcc or raw while measuring and if there is a big difference since I will be getting 5.2-8.4V from the cells.
2:21 pm
misan said…
Dear Johannes,

The problem with battery voltage in your case is that it is too high to safely power Arduino. Because of this a voltage regulator is needed, but unfortunately, the regulator idle current is likely going to exceed by a fair amount the power needed by Arduino to be sleeping.

I'd try to find a way where you could power the board directly from a battery without the need of a voltage regulator in between.
4:03 pm
Post a Comment

Popular posts from this blog

VFD control with Arduino using RS485 link

-
Image
Variable Frequency Drives ( VFD ) allow the control of spindles so speed can accurately be controlled and a detailed acceleration profile for the spindle and reverse rotation can all be handled. In essence a VFD is an three phase inverter for three-phase AC motor. I am using a popular (I mean cheap) Chinese VFD and though the reference manual is not great, I could see there is a built-in RS-485 port. I usually control the start, stop and speed selection using the keyboard on the unit but I thought it will be more useful if I could control everything from the same Arduino is doing our CNC table control. Some cheap RS-485 off eBay and some lines of code later, I can start, stop and change the speed from an Arduino. What a cool thing to have! Some configuration of your VFD are needed before you can use it like that.  You need to set PD163=1 (I am using address 1 in the code). PD=164=1 (for setting serial to 9600bps) and PD165=0 (for using ASCII and 8N1 character format)
Read more

How to get sinusoidal s-curve for a stepper motor

-
Image
After some experimentation, and delving a bit into the math of motion, I realized there can be a significant difference on the motion of a machine by just making small changes. A common and popular approach to smooth one axis of motion is to use a trapezoidal speed pattern, where acceleration and deceleration are uniformly accelerated movements (aka constant acceleration motion) separated by a portion happening at cruising speed. The problem comes with the fact that, while that approach is simple to understand and to code, it does contain sudden changes in the acceleration, that show as spikes on the acceleration derivative, called jerk. These sudden changes in the acceleration translate into undesired vibration in our machines. Most of that can be eliminated by selecting a motion pattern that does not contain sudden changes of acceleration. If we chose a mathematical function for our speed whose second derivative is continuous, then we reduce system vibration quite a lot. One ma
Read more

Importing OpenSCAD designs into Onshape

-
Image
After using Onshape CAD software for a while I am really fond of it. So one natural thing to do, specially once they have released the Instructor's kit is to start using it in the classroom too. But one thing I was not so sure how to do was to use old designs I made using OpenSCAD. It does not mean I am completely quitting using OpenSCAD but suddenly I can see I can do assemblies in Onshape that will look quite nice for showing and documentation purposes if only I could easily import from OpenSCAD. I am glad to report that the route OpenSCAD --> FreeCAD --> Onshape worked brilliantly. Even more when a few tricks were applied. While some people suggest to import CSG files from OpenSCAD to FreeCAD, I have had more success by directly importing SCAD files into FreeCAD. One trick that worked well for me was to get rid of $fn references, so now circles become real circles (or cylinders) in FreeCAD. If a part keeps some $fn references then your cylinders or circles wi
Read more