From: Mark A. <m_a...@co...> - 2008-11-14 17:36:17
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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 > > |