From: Daniel S. <de...@pm...> - 2008-11-14 18:47:50
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The cap will only help with transient current needs. It sounds like you are drawing more current than the regulator can support without dropping out, or your battery voltage is dropping. Measure the battery while the output is dropping to make sure it is capable of supplying the current you need. 2.5 AHr is not that large for this kind of power requirement. -Dan At 10:24 AM 11/14/2008, you wrote: >Hi Mark, > >I'm actually using a Roomba Create as well. I went and bought a 100uF >electrolytic that supports 50V and a 0.1uF that supports the same, but I >still have the same problem with the voltage dropping down to about 4V after >the Wifistix starts up. Any ideas? > >-Russell > > >m_ahlenius wrote: > > > > Hi, > > > > interesting application. I did the same thing last year when I was in > > my last job. I put a verdex on a Roomba (actually Roomba Create). We > > used BT to connect to the Verdex and sent voice recognized commands over > > the BT to control the Roomba. Was fun! Got some pix somewhere. > > > > 'mark > > > > RussellMorin wrote: > >> I have already done the mod that Dave suggested. The battery that I am > >> using > >> is a 14.4V 2500mAh Roomba APS battery pack. Ideally I want to run it > >> through > >> the Roomba, but for now I'm running directly from the battery for > >> debugging. > >> I'll run over to our ECE shop at 1:00 when they open again to see if I > >> can > >> get the caps that you suggested and I'll let you know how it works. > >> > >> Thanks, > >> -Russ Morin > >> > >> > >> m_ahlenius wrote: > >> > >>> Hey, > >>> > >>> let me change that electrolytic cap size. Actually I'd bump it up to a > >>> larger size - more like 100 uF or 200 uF or so. These new ones are > >>> quite small. > >>> > >>> 'mark > >>> > >>> Mark Ahlenius wrote: > >>> > >>>> Hi Russell, > >>>> > >>>> what I would do is to go over to Radio Shack or your electronics parts > >>>> supplier and pick up a small electrolytic capacitor - say 25 to 50 > >>>> micro > >>>> farads (uF) at at least 20 vDC which is the working voltage (greater > >>>> if > >>>> fine). Also get a small 0.1 uF decoupling cap as well with the same > >>>> voltage range.. Both are quite cheap > >>>> > >>>> The decoupling cap usually does not have polarity, so just solder it > >>>> from your 7805 power output to ground. The electrolytic will be > >>>> polarized, so also attach it from the power output to ground, but make > >>>> sure the + side of the cap goes to your power output pin. Both of > >>>> these > >>>> should be as close as possible to the gumstix board. > >>>> > >>>> Let us know if this solves your problem. BTW - what is your battery > >>>> size and voltage? These gumstix devices are power hungry and if you > >>>> don't have enough battery current - that will be your problem. > >>>> > >>>> 'mark > >>>> > >>>> RussellMorin wrote: > >>>> > >>>> > >>>>> Mark, > >>>>> > >>>>> Currently I just have battery power going into the L7805 and the > >>>>> regulated > >>>>> power coming out. I don't know enough electrical engineering to have > >>>>> tried > >>>>> adding caps. I hooked a DVM up to the leads and noticed that the > >>>>> voltage > >>>>> starts to drop off from 5.02 Volts down to 4.83 and dropping. How > >>>>> should > >>>>> I > >>>>> configure my circuit to stop this from happening? > >>>>> > >>>>> Thanks, > >>>>> -Russell > >>>>> > >>>>> > >>>>> m_ahlenius wrote: > >>>>> > >>>>> > >>>>> > >>>>>> Russell, > >>>>>> > >>>>>> out of curiousity, do you have a decent sized cap as well as a small > >>>>>> decoupling cap on the output of the L7805? You might put scope or > >>>>>> DVM > >>>>>> on the power output and see if you can detect a dip in voltage. I > >>>>>> do > >>>>>> recall that the Wifi does suck down some power. > >>>>>> > >>>>>> best, > >>>>>> > >>>>>> 'mark > >>>>>> > >>>>>> RussellMorin wrote: > >>>>>> > >>>>>> > >>>>>> > >>>>>>> Dave, > >>>>>>> > >>>>>>> I am having a similar resetting problem. I have a > >>>>>>> Connex200xm/Robostix/Wifistix setup running Buildroot 1629. It runs > >>>>>>> perfectly fine on a Gumstix power supply, but I'm trying to > >>>>>>> disconnect > >>>>>>> my > >>>>>>> robot from the wall. I'm getting power to the stack through a > >>>>>>> L7805CV > >>>>>>> regulator to give it 5V and up to 1.5 amps. Since the wall wart for > >>>>>>> the > >>>>>>> Gumstix is rated for 5V at 1 amp this should be fine. > >>>>>>> > >>>>>>> Right about when the Wifistix starts to kick in the stack reboots > >>>>>>> and > >>>>>>> goes > >>>>>>> into an infinite reset loop. Are there any mods besides the pullup > >>>>>>> resistor > >>>>>>> mod that I could do to make this work? > >>>>>>> > >>>>>>> Thanks, > >>>>>>> -Russ Morin > >>>>>>> > >>>>>>> Dave Hylands wrote: > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>>> Hi Jostein, > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>>> I received my Gumstix and Robostix two weeks ago for my project > >>>>>>>>> this > >>>>>>>>> fall > >>>>>>>>> at > >>>>>>>>> the Norwegian University for Science and Technology (NTNU). The > >>>>>>>>> first > >>>>>>>>> thing > >>>>>>>>> I noticed was the weird dents on top of one of the chips on the > >>>>>>>>> Verdex > >>>>>>>>> XL6P. > >>>>>>>>> I don't know if they are normal, so I've attached an image of it. > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>> I think I see the dent that you're talking about. It really depends > >>>>>>>> on > >>>>>>>> how it was created. > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>>> The other > >>>>>>>>> image shows how I've connected the Verdex to my computer. The > >>>>>>>>> Verdex > >>>>>>>>> is > >>>>>>>>> plugged into the Robostix, and the Verdex FFUART available from > >>>>>>>>> the > >>>>>>>>> Robostix > >>>>>>>>> is connected to my Atmel STK500 - which also powers the board with > >>>>>>>>> +5V. > >>>>>>>>> The > >>>>>>>>> STK500 contains a level converter and RS232 out which lets me > >>>>>>>>> connect > >>>>>>>>> it > >>>>>>>>> to > >>>>>>>>> my computer. > >>>>>>>>> Using kermit I can connect to the Verdex, and at first it seems > >>>>>>>>> ok, > >>>>>>>>> but > >>>>>>>>> then > >>>>>>>>> it starts resetting. > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>> That's not good. If you have a Wifi chip, then the resetting is > >>>>>>>> normal. If you don't, then I would be inclined to return the > >>>>>>>> gumstix > >>>>>>>> for RMA. > >>>>>>>> > >>>>>>>> -- > >>>>>>>> Dave Hylands > >>>>>>>> Shuswap, BC, Canada > >>>>>>>> http://www.DaveHylands.com/ > >>>>>>>> > >>>>>>>> > ------------------------------------------------------------------------- > >>>>>>>> This SF.Net email is sponsored by the Moblin Your Move Developer's > >>>>>>>> challenge > >>>>>>>> Build the coolest Linux based applications with Moblin SDK & win > >>>>>>>> great > >>>>>>>> prizes > >>>>>>>> Grand prize is a trip for two to an Open Source event anywhere in > >>>>>>>> the > >>>>>>>> world > >>>>>>>> http://moblin-contest.org/redirect.php?banner_id=100&url=/ > >>>>>>>> _______________________________________________ > >>>>>>>> gumstix-users mailing list > >>>>>>>> gum...@li... > >>>>>>>> https://lists.sourceforge.net/lists/listinfo/gumstix-users > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>> > ------------------------------------------------------------------------- > >>>>>> This SF.Net email is sponsored by the Moblin Your Move Developer's > >>>>>> challenge > >>>>>> Build the coolest Linux based applications with Moblin SDK & win > >>>>>> great > >>>>>> prizes > >>>>>> Grand prize is a trip for two to an Open Source event anywhere in the > >>>>>> world > >>>>>> http://moblin-contest.org/redirect.php?banner_id=100&url=/ > >>>>>> _______________________________________________ > >>>>>> gumstix-users mailing list > >>>>>> gum...@li... > >>>>>> https://lists.sourceforge.net/lists/listinfo/gumstix-users > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>> > >>>>> > >>>>> > >>>> > ------------------------------------------------------------------------- > >>>> This SF.Net email is sponsored by the Moblin Your Move Developer's > >>>> challenge > >>>> Build the coolest Linux based applications with Moblin SDK & win great > >>>> prizes > >>>> Grand prize is a trip for two to an Open Source event anywhere in the > >>>> world > >>>> http://moblin-contest.org/redirect.php?banner_id=100&url=/ > >>>> _______________________________________________ > >>>> gumstix-users mailing list > >>>> gum...@li... > >>>> https://lists.sourceforge.net/lists/listinfo/gumstix-users > >>>> > >>>> > >>>> > >>> ------------------------------------------------------------------------- > >>> This SF.Net email is sponsored by the Moblin Your Move Developer's > >>> challenge > >>> Build the coolest Linux based applications with Moblin SDK & win great > >>> prizes > >>> Grand prize is a trip for two to an Open Source event anywhere in the > >>> world > >>> http://moblin-contest.org/redirect.php?banner_id=100&url=/ > >>> _______________________________________________ > >>> gumstix-users mailing list > >>> gum...@li... > >>> https://lists.sourceforge.net/lists/listinfo/gumstix-users > >>> > >>> > >>> > >> > >> > > > > > > ------------------------------------------------------------------------- > > This SF.Net email is sponsored by the Moblin Your Move Developer's > > challenge > > Build the coolest Linux based applications with Moblin SDK & win great > > prizes > > Grand prize is a trip for two to an Open Source event anywhere in the > > world > > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > > _______________________________________________ > > gumstix-users mailing list > > gum...@li... > > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > > > > >-- >View this message in context: >http://www.nabble.com/My-Gumstix-keeps-resetting-tp19638258p20505915.html >Sent from the Gumstix mailing list archive at Nabble.com. > > >------------------------------------------------------------------------- >This SF.Net email is sponsored by the Moblin Your Move Developer's challenge >Build the coolest Linux based applications with Moblin SDK & win great prizes >Grand prize is a trip for two to an Open Source event anywhere in the world >http://moblin-contest.org/redirect.php?banner_id=100&url=/ >_______________________________________________ >gumstix-users mailing list >gum...@li... >https://lists.sourceforge.net/lists/listinfo/gumstix-users **************************************************************************** The lame man who keeps the right road outstrips the runner who takes a wrong one. The more active and swift the latter is, the further he will go astray. -Francis Bacon, essayist, philosopher, and statesman (1561-1626) **************************************************************************** Daniel E. Sampson Instrument Engineer A232 Earth and Marine Sciences University of California Santa Cruz, CA 95064 dsa...@es... (831) 459-4992 office (831) 359-9075 cell (831) 459-3074 FAX **************************************************** |