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Groups > comp.arch.embedded > #20750
| Subject | Re: Mecrisp on the TI Stellaris Launchpad |
|---|---|
| Newsgroups | comp.arch.embedded, comp.lang.forth, comp.sys.raspberry-pi |
| From | Alan Adams <alan@adamshome.org.uk> |
| Date | 2015-04-20 09:33 +0100 |
| Message-ID | <e10132b754.Alan.Adams@iyonix.adamshome.org.uk> (permalink) |
| References | (7 earlier) <mgrket$1d0$1@dont-email.me> <RRdYw.257010$Zf4.118346@fx22.am4> <mgrsbf$um9$2@dont-email.me> <2ivYw.272005$JH2.257361@fx11.am4> <mh14qa$u9a$1@dont-email.me> |
| Organization | Orpheus Internet Services |
Cross-posted to 3 groups.
In message <mh14qa$u9a$1@dont-email.me>
rickman <gnuarm@gmail.com> wrote:
> On 4/18/2015 12:06 PM, mm0fmf wrote:
>> On 17/04/2015 22:02, rickman wrote:
>>> I was commenting on the facts that there is a quarter volt lost across
>>> the rPi
>>
>> It doesn't matter how much "is lost" because the final voltage is within
>> spec.
> You are confused. The only reason why the output voltage is in spec is
> because the input voltage is well above the nominal voltage required on
> the input. With another power module the output voltage would be
> outside of spec and even now, the output is not able to supply much
> current. Connect a device that draws more current and the voltage sags
> more.
> This is not so much about the USB spec as it is the design of the rPi
> which creates a lot of voltage drop on what should be very nearly a wire
> with nominal resistance.
and to make it worse, and fluctuations in the current drawn will
produce fluctuations in the voltage. Checking with an oscilloscope is
the only realistic way to see whether this is affecting the problem.
>> I don't know about the hub and PHY on the Pi, but all the PHYs we
>> produce have the ability to disable VBUS on each port and can signal
>> over current conditions. When a device pulls too much current you signal
>> the USB MAC and it tells the PHY to kill VBUS. The missing volts will be
>> loss in the PHY VBUS switch most likely.
> Such a switch would typically have a resistance of low mOhms and create
> a correspondingly low voltage drop... much less than the 0.25 volts we
> are seeing in the rPi.
>> I don't work with our PHYs directly but only with the USB MACs we
>> produce so I can't recall off the top of my head if the over current is
>> as programmable as the current the device claims during enumeration.
>> Devices specify their max current requirements in multiples of 2mA
>> units. Before enumeration, the spec allows 100mA and I'm fairly sure our
>> PHYs will signal over current if something tries to draw much more than
>> 100mA. Once enumerated, again I'm fairly sure the over current level is
>> programmable.
>>
>>> and that the launchpad seems to reset when I type on the USB
>>> keyboard.
>>
>> If the launchpad lies during enumeration then this can happen. It's not
>> helped by the early Pi hardware being a bit more than flakey.
> Bingo.
>>> Maybe it's not voltage related, but the quarter volt drop is
>>> unexpected
>>
>> Not when you know there are switches between the power rail and VBUS as
>> previously stated.
> The rPi does not have switches in the power path I believe. But if it
> does, they should be designed for a much lower voltage drop than a
> quarter volt, hence the problem.
>>> and there are plenty of cases where even an older mouse, like
>>> the one I have, can't be powered through the rPi.
>>
>> I have lots of devices that work perfectly with a Pi as long as they are
>> connected before the Pi (model B, 512M) is booted. Plugging them in once
>> booted normally results in a crash. Which is a shame as USB is designed
>> to be hot-pluggable.
>>
>> I should really say that I am shocked, nay stunned to find that a £30
>> single board PC which can be battery powered that runs Linux and
>> provides a metric shit-load of IO in addition to Ethernet and USB has a
>> number of gotchas and issues. ;-)
> I find your description of the rPi to be interesting. Battery powered
> is a bit tongue in cheek as this level device is on par with phones and
> tablets which can't be away from a power plug for hours rather than
> days. I think of "battery powered" as describing equipment that can be
> left unattended for many days without an external power source. But
> whatever, one man's battery is another man's RTG. lol
> Enjoy
--
Alan Adams, from Northamptonshire
alan@adamshome.org.uk
http://www.nckc.org.uk/
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Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-02 21:08 -0400
Re: Mecrisp on the TI Stellaris Launchpad sbattazzo@gmail.com - 2015-04-13 16:18 -0700
Re: Mecrisp on the TI Stellaris Launchpad sbattazzo@gmail.com - 2015-04-13 16:25 -0700
Re: Mecrisp on the TI Stellaris Launchpad sbattazzo@gmail.com - 2015-04-13 16:33 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-13 21:45 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-13 21:47 -0400
Re: Mecrisp on the TI Stellaris Launchpad sbattazzo@gmail.com - 2015-04-14 07:33 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-14 14:38 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-16 14:24 -0700
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-16 15:11 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-16 23:37 -0400
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-16 20:59 -0700
Re: Mecrisp on the TI Stellaris Launchpad Mel Wilson <mwilson@the-wire.com> - 2015-04-17 13:16 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 00:19 -0400
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-16 21:56 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 14:47 -0400
WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking rickman <gnuarm@gmail.com> - 2015-04-17 15:12 -0400
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking Martin Gregorie <martin@address-in-sig.invalid> - 2015-04-17 20:14 +0000
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking rickman <gnuarm@gmail.com> - 2015-04-17 16:59 -0400
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking David Brown <david.brown@hesbynett.no> - 2015-04-18 10:00 +0200
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking rickman <gnuarm@gmail.com> - 2015-04-18 09:32 -0400
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking Martin Gregorie <martin@address-in-sig.invalid> - 2015-04-18 15:15 +0000
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking rickman <gnuarm@gmail.com> - 2015-04-18 11:31 -0400
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking Niklas Holsti <niklas.holsti@tidorum.invalid> - 2015-04-18 19:21 +0300
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking rickman <gnuarm@gmail.com> - 2015-04-19 16:39 -0400
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking Alan Adams <alan@adamshome.org.uk> - 2015-04-18 18:52 +0100
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking "Rod Pemberton" <bork@lllljunkqwer.cpm> - 2015-04-18 18:55 -0400
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking The Natural Philosopher <tnp@invalid.invalid> - 2015-04-19 09:13 +0100
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking Dimiter_Popoff <dp@tgi-sci.com> - 2015-04-19 13:22 +0300
Re: WAS: Mecrisp on the TI Stellaris Launchpad IS: Thunderbird Line Breaking David Brown <david.brown@hesbynett.no> - 2015-04-19 22:09 +0200
Re: Mecrisp on the TI Stellaris Launchpad mm0fmf <none@mailinator.com> - 2015-04-17 21:15 +0100
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 17:02 -0400
Re: Mecrisp on the TI Stellaris Launchpad mm0fmf <none@mailinator.com> - 2015-04-18 17:06 +0100
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-19 16:57 -0400
Re: Mecrisp on the TI Stellaris Launchpad Alan Adams <alan@adamshome.org.uk> - 2015-04-20 09:33 +0100
Re: Mecrisp on the TI Stellaris Launchpad mm0fmf <none@mailinator.com> - 2015-04-20 18:03 +0100
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-21 01:16 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 20:20 -0400
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-17 17:24 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 20:40 -0400
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-17 17:57 -0700
Re: Mecrisp on the TI Stellaris Launchpad Mel Wilson <mwilson@the-wire.com> - 2015-04-18 02:14 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-18 02:05 -0400
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 10:16 +0200
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-18 09:56 -0400
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 17:46 +0200
USB serial ports, was: Re: Mecrisp on the TI Stellaris Launchpad Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2015-04-18 18:34 +0000
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 10:04 +0200
Re: Mecrisp on the TI Stellaris Launchpad Jan Coombs <Jan-54 <jenfhaomndgfwutc@murmic.plus.com>> - 2015-04-18 09:38 +0100
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-18 11:04 -0400
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 17:54 +0200
Re: Mecrisp on the TI Stellaris Launchpad hal-usenet@ip-64-139-1-69.sjc.megapath.net (Hal Murray) - 2015-04-18 15:36 -0500
Re: Mecrisp on the TI Stellaris Launchpad Theo Markettos <theom+news@chiark.greenend.org.uk> - 2015-04-23 07:59 +0100
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-25 14:35 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-25 15:44 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-05-08 12:00 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-05-10 03:36 -0400
Re: Mecrisp on the TI Stellaris Launchpad Theo Markettos <theom+news@chiark.greenend.org.uk> - 2015-05-10 10:32 +0100
Re: Mecrisp on the TI Stellaris Launchpad Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2015-05-10 12:56 +0300
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-05-10 10:48 -0400
Re: Mecrisp on the TI Stellaris Launchpad The Natural Philosopher <tnp@invalid.invalid> - 2015-05-10 16:05 +0100
Re: Mecrisp on the TI Stellaris Launchpad Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2015-05-10 23:26 +0000
Re: Mecrisp on the TI Stellaris Launchpad Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2015-05-10 09:37 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-05-10 11:16 -0400
Re: Mecrisp on the TI Stellaris Launchpad Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2015-05-10 23:42 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-05-11 02:17 -0400
Re: Mecrisp on the TI Stellaris Launchpad albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-05-10 11:41 +0000
Re: Mecrisp on the TI Stellaris Launchpad Theo Markettos <theom+news@chiark.greenend.org.uk> - 2015-05-10 16:56 +0100
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-05-10 13:01 -0400
Re: Mecrisp on the TI Stellaris Launchpad lasselangwadtchristensen@gmail.com - 2015-04-18 12:13 -0700
Re: Mecrisp on the TI Stellaris Launchpad stephen@mpeforth.com (Stephen Pelc) - 2015-04-18 19:22 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-19 17:04 -0400
Re: Mecrisp on the TI Stellaris Launchpad Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2015-04-20 13:24 +0300
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-22 13:23 -0400
Re: Mecrisp on the TI Stellaris Launchpad Dimiter_Popoff <dp@tgi-sci.com> - 2015-04-22 20:44 +0300
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-22 13:51 -0400
Re: Mecrisp on the TI Stellaris Launchpad Waldek Hebisch <hebisch@math.uni.wroc.pl> - 2015-04-22 19:10 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-22 15:31 -0400
Re: Mecrisp on the TI Stellaris Launchpad Waldek Hebisch <hebisch@math.uni.wroc.pl> - 2015-04-23 02:08 +0000
Re: Mecrisp on the TI Stellaris Launchpad Waldek Hebisch <hebisch@math.uni.wroc.pl> - 2015-04-24 02:52 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-25 14:40 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-25 15:42 -0400
Re: Mecrisp on the TI Stellaris Launchpad sbattazzo@gmail.com - 2015-04-21 09:34 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-22 14:57 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-22 15:35 -0400
Re: Mecrisp on the TI Stellaris Launchpad albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-17 10:52 +0000
Re: Mecrisp on the TI Stellaris Launchpad Dimiter_Popoff <dp@tgi-sci.com> - 2015-04-17 14:05 +0300
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-17 07:56 -0700
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-17 17:26 +0200
Re: Mecrisp on the TI Stellaris Launchpad glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-17 17:01 +0000
Re: Mecrisp on the TI Stellaris Launchpad Blajrs Jrolrsen <boegre@no.com> - 2015-04-17 13:36 +0000
Re: Mecrisp on the TI Stellaris Launchpad anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-17 14:42 +0000
Re: Mecrisp on the TI Stellaris Launchpad Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2015-04-18 00:25 +0200
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 20:03 -0400
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-17 17:14 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 20:26 -0400
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-17 17:32 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 20:47 -0400
Re: Mecrisp on the TI Stellaris Launchpad albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-18 08:47 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-18 11:19 -0400
Re: Mecrisp on the TI Stellaris Launchpad albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-18 15:52 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-19 17:07 -0400
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-06-09 03:04 -0400
Re: Mecrisp on the TI Stellaris Launchpad Robert Wessel <robertwessel2@yahoo.com> - 2015-04-18 00:11 -0500
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 10:32 +0200
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-18 11:26 -0400
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 17:57 +0200
Re: Mecrisp on the TI Stellaris Launchpad Paul Rubin <no.email@nospam.invalid> - 2015-04-18 09:42 -0700
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-19 17:11 -0400
Re: Mecrisp on the TI Stellaris Launchpad Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2015-04-18 12:19 +0200
Re: Mecrisp on the TI Stellaris Launchpad Dimiter_Popoff <dp@tgi-sci.com> - 2015-04-18 15:16 +0300
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 19:57 +0200
Re: Mecrisp on the TI Stellaris Launchpad Dimiter_Popoff <dp@tgi-sci.com> - 2015-04-18 23:11 +0300
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-19 21:32 +0200
Re: Mecrisp on the TI Stellaris Launchpad Dimiter_Popoff <dp@tgi-sci.com> - 2015-04-19 23:04 +0300
Re: Mecrisp on the TI Stellaris Launchpad anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-18 09:15 +0000
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 12:17 +0200
Re: Mecrisp on the TI Stellaris Launchpad anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-18 13:08 +0000
Re: Mecrisp on the TI Stellaris Launchpad David Brown <david.brown@hesbynett.no> - 2015-04-18 20:17 +0200
Re: Mecrisp on the TI Stellaris Launchpad anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-20 15:33 +0000
Re: Mecrisp on the TI Stellaris Launchpad rickman <gnuarm@gmail.com> - 2015-04-17 14:52 -0400
Re: Mecrisp on the TI Stellaris Launchpad albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-17 20:06 +0000
Re: Mecrisp on the TI Stellaris Launchpad lasselangwadtchristensen@gmail.com - 2015-04-16 16:18 -0700
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