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Does the Lego USB IR tower, when set to long range, sometimes draw more than the 500mA allowed? Or do laptops generally not reliably supply 500mA? Or are we facing some deeper analog issue here, like not ramping up to 500mA from less mA fast enough (...) (22 years ago, 12-Feb-03, to lugnet.robotics.rcx)
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| | Re: no long range IR from laptop says Lego
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Kindly offline I am informed: yes indeed, some laptop designs have been seen to support less than half of the specified 500mA max load for USB bus power. I wonder how many mA the USB IR tower does need. Pat LaVarre (22 years ago, 12-Feb-03, to lugnet.robotics.rcx)
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| | Re: no long range IR from laptop says Lego
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(...) Its USB descriptors say there are two configurations with 100mA (I think these are for low and medium power), and two that require 500mA (high power mode). The LEGO USB Tower Interface Reference doesn't go into more details. Jürgen (22 years ago, 12-Feb-03, to lugnet.robotics.rcx)
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| | Re: no long range IR from laptop says Lego
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(...) Fascinating stuff, thanks again. In particular, I didn't know Anyone had persuaded Windows to respond intelligently to Usb Configuration's of variable power. Anybody know if these descriptors already appear on the web somewhere? Else please (...) (22 years ago, 13-Feb-03, to lugnet.robotics.rcx)
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| | Re: no long range IR from laptop says Lego
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(...) No idea. I think these values are used for accounting, to ensure that all devices together don't exceed available power. But I don't know how well this is implemented. (...) Linux makes them available in readable form in /proc/bus/usb/devices (...) (22 years ago, 14-Feb-03, to lugnet.robotics.rcx)
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| | Re: no long range IR from laptop says Lego
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Use a powered USB hub with the laptop. The power required for the USB IR Tower will come from the powered hub, rather than the laptop. - Rob (...) (22 years ago, 15-Feb-03, to lugnet.robotics.rcx)
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