3 Replies Latest reply on Dec 28, 2014 6:08 AM by deium

    Any software way to completely shut off power to Arduino shield?


      I am about 99% sure the answer is no, but on the off chance that I am wrong, I thought I would ask.


      If I am running one of my Edisons on a Hexapod, using Lipo battery (3S), and I detect that lipo is dropping below some threshold voltage.  I would like to shut things off as much as possible, as to not kill yet another lipo battery.  Killed one two days ago, when I thought I had turned it off, but obviously I had not.


      With the PhantomX,  I can currently (and should) do some things to help reduce this, like when the voltage gets too low, I can tell the AX servos to turn their motors off.  Their processors, will probably still use a little power.  I can also do things like issue a system command of: shutdown now.


      The shutdown appears to remove power from the USB buss, so the USB2AX that I have connected as well as the sound card, get un-powered.


      However the shields show now signs of losing power.  The XBee shield is still blinking LEDS - I can probably minimize some of this by probably issuing some command to the xbee to power down or at least go to sleep.  Also could instead go to XBee connected by USB, which I will do when using mini-breakout.


      Some of the time I have an Adafruit TFT display on it, who eats some power, especially the back light.  I might be able to reduce some of this, by setting up a jumper on the display, to have the backlight controlled by IO pin... Possibly with PWM to control brightness.  Hopefully when no power on Edison hopefully the backlight will be off...


      Again I think I already know the answer (NO). But maybe I will get surprised.



        • 1. Re: Any software way to completely shut off power to Arduino shield?


          You're more hardware than I, but would there be away to grab a different pin

          (mini breakout exposes more than Arduino - so is there a way to expose an extra pin)

          that you could use to run through a swtich -

          <power from board> to  <switch via extra GPIO> to <power on shield>

          throwing GPIO triggers the switch to power shield on/off?

          • 2. Re: Any software way to completely shut off power to Arduino shield?

            Just to follow up here. I believe most of the shields that I use, get their power directly from the +5v pin that comes in.  Many of them have their own voltage regulator that converts the +5v to which ever voltages that they need.


            It is also my belief that the +5v that goes to the +5v of the shield comes directly from the voltage regulator maybe through some other discrete components and not under any control of the processor, so this may be hard to change without modifying the board.


            One option would be to take the bottom shield, and bend out the +5v pin such that it does not go into the socket.  Then use a jumper wire that I could then go to some relay, that I could control by any IO pin, that would turn on when power is attached, which then routes power to the shield.  But it would be nice if this could be done internally.

            • 3. Re: Any software way to completely shut off power to Arduino shield?



              I think you are right.  Edison has bee my first non pc hardware, from everything I have seen the shield power pins are direct.  Lots of shields coming with a power button/switch on the shield - but not programmable.  Of all the code I have seen so far (lots and lots and .. ) I haven't run across anything yet for controlling the power pins through code.  It was the only thing I could think of was to create-a-switch.   Hope your holidays were wonderful.