[OZAPRS] [aprssig] Can I run a GPS18 from the +5v on the USBcable?

[Dave Baxter]

Sorry..

Only 100mA without software negotiation for a High Power device.  There
should be current limiting devices on the PC mother board, but take care
anyway, and do not have more than 10uF of "visible" decoupling on the 5V
line, or the plug in surge could upset other attached devices, or the
host PC, at best, a reboot, at worst a lockup!....

After propper "Negotiation and enumeration", then up to 5 "Units" of
current can be drawn (500mA)  But, you must negotiate for that with the
host, and it's not a trivial task either...

There is a lot on this, on the USB developer website, easy to find with
google, big brother or otherwise..

External keyboard or mouse sockets are another source of power if
needed, but I'd be careful taking too much out of them too...

Dave G0WBX.



> -----Original Message-----
> From: Darryl Smith [mailto:Darryl at radio-active.net.au] 
> Sent: Sunday, April 30, 2006 3:39 AM
> To: 'VK / ZL APRS Users'; vk4tec at tech-software.net; 'TAPR 
> APRS Mailing List'
> Subject: RE: [OZAPRS] [aprssig] Can I run a GPS18 from the 
> +5v on the USBcable?
> 
> USB will supply a maximum of 100 mA per port at 5V to a 
> device. Commonly ports can supply five units of power to a 
> device, or 500 mA to a port, but this will be dependant on 
> what else is plugged in.
> 
> Intelligent devices may communicate with the controller to 
> discuss power requirements and shut down if required. Since 
> you are not worrying about using the USB power control I 
> would say that you can pull about 500 mA commonly from the port
> 
> Darryl