Topic: Powering Chumby from Roomba?

Hey everyone, I just bought a new Roomba and was thinking of making it into a Chumby controlled robot. I bought like 4 Insignia Infocast 3.5s last year on sale, and they're just waiting to be used!! I have been looking at the RooStick ( which allows you to break out the battery Power from the roomba. I'm worried that the Chumby will draw too much power, however, as a comment there said that the device locks up if it goes over a certain amount. Preferably I'd like to keep the screen attached, but obviously that's going to pull more power, so if needed I could leave it off... I do also know that the Insignia has a few things broken out like the power, so presumably that's where I'd hook up the RooStick wires? Also, I wonder if the Chumby Hacker board for some reason has lower power requirements (it does, of course not come with the screen, but otherwise, it should be more or less the same, powerwise?). I really want to power the Chumby with the Roomba's battery because of the charging base feature - I don't want the chumby running off of some other battery pack that will die randomly while the Roomba is still in use. If this isn't at all feasible, are there other directions I can go in, like the BeagleBoard? I want to use a computer and not a microcontroller as I need easy access to USB devices and communication over WIFI.

Re: Powering Chumby from Roomba?

I feel like I should have bought more than one Infocast 3.5" when they were $40....

I don't think you can count on the Infocast staying under the 500mA the comment at SparkFun specifies as the load limit through the Roomba communication cable. The Infocast power adapter is 5V 2000mA (but who knows, you should try measuring the current consumption).

The Chumby Hacker Board wouldn't be all that different from the Infocast, except for the screen as you say.

The Chumby is a fine (and cheap) computer to put on your Roomba, you'll just have to power it some other way than through the communication cable, either with a new 5V regulator off the battery, or tapping off an existing regulator that has enough unused current headroom.

Re: Powering Chumby from Roomba?

I've measured the CHB and CHB+WiFi on my bench supply.  WiFi about doubles the draw -- the two together are about 400 mA average, IIRC, but my memory is a little fuzzy on the numbers right now.  Is there another way to get power out of the Roomba? (I guess you aren't using a iRobot Create base, which gives you access to the 14V battery). I'm tapping the battery in a Neato XV-11 and using a DigiKey p/n 811-2196-5-ND voltage regulator.  Another thought, provide a battery for the Chumby that is charged off the Roomba.  Doesn't have to be large at all, just enough to cover power sags.  In fact, seems like the LiPo port on the CHB should do just that for you already, with a built-in charge controller.  Although I guess that doesn't limit the current draw from the Roomba.

Re: Powering Chumby from Roomba?

Thanks for the replies. Does anyone know of any tutorials to tap into the battery directly? Is that safe?? And if I powered an external battery from the RooStick and plugged that into the Chumby, would the charging/power drops average out, or slowly drain the extra battery over time?