cimo Posted July 8, 2008 Report Share Posted July 8, 2008 In the new GM5 page it s stated that a USB host limits the max. current drain to 500 mA.these specs are valid for USB 2.0 but not for USB 1.1 Quote Link to comment Share on other sites More sharing options...
TK. Posted July 8, 2008 Report Share Posted July 8, 2008 I'm not sure what you want to say, and it's unfair that you don't propose an alternative wording.Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
cimo Posted July 9, 2008 Author Report Share Posted July 9, 2008 I'm not sure what you want to say, and it's unfair that you don't propose an alternative wording.Best Regards, Thorsten.ok sorryi meant that USB 1.1 can t ALWAYS offer the same current as USB 2.0, this is especially true when used with older machines.I can t find proper documentation right now but i ll dig on it later on.This could be particularly useful to know on "my box worked perfectly until today.." situation, i do believe that a box with 2 COREs and a LCD wouldn t work on my old PIII machine with USB 1.1 interface.Simone Quote Link to comment Share on other sites More sharing options...
dj3nk Posted July 11, 2008 Report Share Posted July 11, 2008 i believe every usb port can deliver up to 500mA (=highpower) ( 100mA=lowpower ). So it IS a spec of the USB standard and not just for 2.0 .greetz Quote Link to comment Share on other sites More sharing options...
stryd_one Posted July 11, 2008 Report Share Posted July 11, 2008 I checked on this at work today, here's the lowdown:The spec always specified that each port should deliver a max of 5V@500mA, in 100mA increments, for 1.1 and 2.0 and 2.x. Some PC motherboard manufacturers ignored that, or made design errors (yeh right) and their machines didn't always deliver as much as they should.This is a similar situation to the JDM thing - in a nutshell: When the PC isn't a piece of crap, it works as designed ;DPersonally, being the rough b*stard I am, my opinion is: if people are gonna support this dodgy behaviour from manufacturers by buying cheap PC's, let them figure it out themselves, and see how much the cheap PC really costs :PSO:a USB host limits the max. current drain to 500 mA.Is true, 100%. Anything else, doesn't meet the spec, so it's not USB, technically speaking (in the same way that those old DRM'd Sony CDs were not really CD's) I'm unaware of any machines that deliver more than that, but that won't be a problem anyway so isnt worth mentioning. Perhaps if TK feels the need to update the wording, he could try:a USB host limits the max. current drain to 500 mA. Some rare, buggy machines may supply less than this specification. Quote Link to comment Share on other sites More sharing options...
nILS Posted July 11, 2008 Report Share Posted July 11, 2008 When the PC isn't a piece of crap, it works as designed ;DI knew I was gonna have problems with that thing ;-) Quote Link to comment Share on other sites More sharing options...
cimo Posted July 11, 2008 Author Report Share Posted July 11, 2008 I knew I was gonna have problems with that thing ;-)buy a Mac and be on the safe side [me=cimo]hides under the desk....[/me]i did my own little research and yes i was wrong on saying that it was "out of specs", "offcially" it s not out of specs.. nevertheless riding around the net about USB power specs you ll see how everybody agrees that USB doesn t really go along with the words STANDARD and SPECIFICATION but unfortunately it goes along and very well with the word massively spread around... and we all know that the fact that all flies go to shit doesn t mean that shit is good.dotIt is probably useless to keep on this discussion (or not?) and what is stated on the GM5 is eventually correct, it was not ERRATA at all, maybe it just needed some add-on like "hey guys in the real world you could encounter this and that problem".My wrong, my apologies TK.When the PC isn't a piece of crap, it works as designed Grinthen we have to assume that:-Either a lot of PCs out there are pieces of crap-Or the definition of piece of crap is in the real world "an average PC"-or both ;)"Unstardardized" USB power management is so common that most of external USB HDD case have a double plug so that they can draw double power from the PCMy 2.5HDD 120Gb 7200rpm with only one plug will run just on some machines. The spec always specified that each port should deliver a max of 5V@500mA, in 100mA incrementscan you link me to this spec? afaik USB standard recognizes just high power and low power devices, nothing in between, i d like to know this once for all.Simone Quote Link to comment Share on other sites More sharing options...
doc Posted July 11, 2008 Report Share Posted July 11, 2008 ... and btw:If anyone has a problem with 500mA: Built a psu for your GM5's and ignore the specs ! ;DgreetsDoc Quote Link to comment Share on other sites More sharing options...
Gerrit Posted July 11, 2008 Report Share Posted July 11, 2008 As far as I remember every conform USB device must start with a maximum current of 100mA. After initialization the host can allow the device to drain more current - up to 500mA. I had to fight with it when designing an USB connected infrared emitter for remote control.The maximum requested value has to be put into the device descriptor.So work bus-powered 4-fold hubs: 4*100mA for the devices, 100mA for the hub itself = 500 mA from the host.If you put a high-power device in a bus-powerd hub the device will recognized, but shows up the exclamation mark and doesn't work.Basically a 5 port MIDI interface should work without problem as high-power since MIDI is a current loop with just around 10mA. Quote Link to comment Share on other sites More sharing options...
cimo Posted July 11, 2008 Author Report Share Posted July 11, 2008 Basically a 5 port MIDI interface should work without problem as high-power since MIDI is a current loop with just around 10mA.sure, the issue comes only if you try to power let s say a CORE+LCD from USB. Quote Link to comment Share on other sites More sharing options...
TK. Posted July 11, 2008 Report Share Posted July 11, 2008 I'm still waiting for a 100% sufficient wording which makes cimo happy. ;)Btw.: the USB powering topic isn't new to me, see also http://soundwidgets.com/smf/index.php?topic=158.msg575#msg575 and http://soundwidgets.com/smf/index.php?topic=66.0. It's also clear to me, that many desktop PCs/notebooks don't really deliver 500 mA (the reason why many USB devices provide a separate power plug). Personally, I would never power my MIDIboxes via USB anyway to save my computers, but people are asking for this frequently......so, before wasting time in discussing about this "grey area": does anybody know some links to reliable reports/articles?Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
cimo Posted July 11, 2008 Author Report Share Posted July 11, 2008 I'm still waiting for a 100% sufficient wording which makes cimo happy. Winkhttp://ucapps.de/mios/midibox64e_v2_2a.zipmain.asm line 7 ;)using USB s power has always been tempting to me and i had some good results, i think that a DC-DC converter (stepup+stepdown) may help preventing voltage drops due to lack of power on unstable situations but surely won t help where there isn t just enough juice.....so, before wasting time in discussing about this "grey area": does anybody know some links to reliable reports/articles?not me! nothing "official" enough atm just a lot of blurbing Quote Link to comment Share on other sites More sharing options...
stryd_one Posted July 12, 2008 Report Share Posted July 12, 2008 buy a Mac and be on the safe side [me=cimo]hides under the desk....[/me]....then we have to assume that:-Either a lot of PCs out there are pieces of crap-Or the definition of piece of crap is in the real world "an average PC"-or both ;)A Mac is a PC! PC = Personal Computer. You're officially the biggest fanboy I know ;Dcan you link me to this spec? afaik USB standard recognizes just high power and low power devices, nothing in between, i d like to know this once for all.Dammit you made me read the spec. I was happy to ask the engineers at work and just believe them hehehe... but it turns out that they know ;)Universal Serial Bus Revision 2.0 specification7.2.1 Classes of DevicesThe power source and sink requirements of different device classes can be simplified with the introduction of theconcept of a unit load. A unit load is defined to be 100 mA. The number of unit loads a device can draw is anabsolute maximum, not an average over time. A device may be either low-power at one unit load or high-power, consuming up to five unit loads. So yeh, low-power is one unit, high power is up to 5 units. Quote Link to comment Share on other sites More sharing options...
cimo Posted July 12, 2008 Author Report Share Posted July 12, 2008 Quote from: cimo on Yesterday at 16:53buy a Mac and be on the safe side* cimo hides under the desk........QuoteWhen the PC isn't a piece of crap, it works as designed Grinthen we have to assume that:-Either a lot of PCs out there are pieces of crap-Or the definition of piece of crap is in the real world "an average PC"-or both WinkA Mac is a PC! PC = Personal Computer. You're officially the biggest fanboy I know Grin[me=cimo]flirts with Ms Job but is officially married to Ms Torvald.Since he broke up with Ms Gate they can t talk to each other anymore.[/me] Quote Link to comment Share on other sites More sharing options...
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