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How good is JVMs in embedded systems?

vish

Hello element14,

 

I just watched this webinar Home Automation at Your Fingertips with Eclipse SmartHome and openHAB. In that, the developers are telling that they are trying to develop the software with pure Java implementation as it will be portable across different devices.

I wonder how effective is running JVMs in an embedded system. With my experience with desktop JVMs, they are resource hungry relative to native C/CPP codes. In embedded systems also, I assume, this will be the case. But as an embedded designer, my focus will be more on cutting down the resource utilization. Then how well JVMs fit into this picture? I'm concerned about CPU utilization and power consumption.

And how well is my Java codes portable in embedded systems? Don't we have to rewrite the device drivers for GPIO and special hardware access? How better this is from having a separate arch dependent module in my C/C++ project and rewrite only that part while porting to a new hardware?

  • I only have experience with OpenHAB running on Raspberry Pi and Windows PC's.  It's super slow to start up on the Pi, and using top, I get 37% of 512MB ram and 1.3% cpu utilization when idle.  But it takes like 10 minutes for the OpenHAB app to start up on startup.  And the interface isn't very speedy.

     

    However, the Raspberry Pi is kind of bottom of the barrel...on other dual core systems OpenHAB runs much smoother.

  • in reply to electronichamsters

    Hi Eric,

    First of all congrats for being a finalist in FMN challenge.

    My actual doubt is about openHAB with rPi only. Startup time of 10 mins!! Isn't it too long image

     

    -vish

  • in reply to vish

    Thanks Vish.  I was hoping to make it into the top 15, but I guess the competition tight for this one.

     

    As a non-commerical DIY thing, I guess 10 minutes is ok,  It's ran for a couple months at my house, very stable, even if kind of power hungry.

     

    I've wondered about whether OpenHAB could be commercialized.  Put a Raspberry Pi board inside a plastic router box and run OpenHAB on it for the most functional home automation around image.  But I guess it would be weird if your router takes 10 minutes after powering up to be functional.  I like that the Eclipse license, the future OpenHAB 2.0, is very permissive and allows commercial use.

  • in reply to electronichamsters

    Ever rebooted a Cisco router ... its 3 mins.

     

    I suspect the target market is larger commercial so running a RPi is not really the ideal use case.

    It will be interesting.

     

    Eric

    Unfortunately not everyone can make the finalists, but I'm pleased to see they have added some extras.

    For the Wireless Challenge there were extras provided by the sponsor as it went on, so it's entirely possible this may also happen here.

     

    Your solutions are very good and I would suggest trying to stick with the sponsors as much as possible.

    EnOcean do have other units to provide energy, so if you can design something to use them and their RF units .... you never know.

     

    Mark