Topic: USB Device not recognized
Date: July 19th – 2005
There are several issues/rules with USB that are not common knowledge:
1- Internal USB ports are current limited to 500 milliamps & a lot of
Power Supplies only have 2 –2 ½ amps of USB Power – The use of USB
HUB with an external supply is necessary for USB POWERED DEVICES –
such as ZIP Drives – Scanners – Memory Readers – Also many of these
HUBS have a – (EXT – INT ) Power Switch . . . TOTAL CURRENT of HUB
IS GOING TO BE : THE RATING OF THE HUB SUPPLY
2- Use the internal USB Ports for USB devices that draw <260 ma & USE HUBS
(with external power supply) for the “Power Hogs” . . .The control lines from
the HUB to PC is < 4 ma demand on PC Power Supply
3- There are settings to be made in BIOS (1.1) – (2.0) or (1.1 & 2.0)
4- There is also a setting in BIOS about using Keyboard & Mouse for wake up
5- Also this feature requires a Power Supply that can provide 2 amps or more on the
+5VSB & requires a jumper to be connected & TOTAL CURRENT must not
EXCEED POWER SUPPLY - - KNOW THY CURRENT DRAW - -
6- There are 2 or 3 – USB Header Connector/Header that require jumpers
and wiring that are often wired wrong – loose – or not connected
7- Usually the Front USB ports (USB56) are not wired or are in error
8- The 2 or 4 USB ports that are near the Keyboard & Mouse Ports are hard
wired and are the most reliable – (USB12 or USB34).
9- Usually Drivers are installed 1st without hardware attached (to comply
with “Plug & Play” . . .Then turn off PC – Connect device – Turn PC On
and “New Device” will be found
10- Many drivers are not “Microsoft approved” – many work – few do not-
generally you can find a driver in driver section of PC that will work
11- Win – 98 drivers do not work; except on Win98 OS
12- Device Manager is good place to look 1st – You can even measure current
draw from the device
13- Some devices such as drives – Cameras – Memory Card Readers require
permission to disconnect before ejecting or just pulling the plug or turn off –
There will be a USB icon in Start Tray that you left click & all USB that need
permission will be listed - (Ones that are connected at the time) Left Click this icon & then left click the device in menu & you will get a message of:
(Yea or Nay) about disconnecting device.
14- If you have a ZIP drive – it is best to have an icon on desktop to right click & to
left click “EJECT”- (on drop down/up menu)- to eject a disk. Otherwise if you use the disk eject button – Zip drive may not be recognized & SYSTEM RESTART will be required
15- Same with using a Memory Reader Card/chip – DO NOT PULL CARD OUT of
slot, before having permission to do so – and don’t turn Camera off or disconnect without permission
To Original Poster – (redgreti) – Several issues apply here –
Are you using a HUB with external supply . . .and is supply connected properly –
(both AC-Power & DC-Power) & if there is a Selector Switch – Is it set to “Ext”.
These devices will draw the 500 ma & I suggest using a HUB for it, with external power supply.
Also your driver may be an issue . . .may not be Microsoft approved . . . That is probably the case if it does this every time you remove a chip . . .
The problem of going into standby & loosing control when coming back to the active state could be related to driver.
When you do restart system . . . .does the device work ok or do you have to shut down – remove USB cable – Power back ON & then reconnect USB Cable??
Do you have a USB Keyboard and/or USB Mouse? What activates/ brings system from Standby to Active? A USB device? such as mouse or keyboard?
What is probably happening is: You are shutting down the USB device & then you are turning power back on . . .you are probably causing a power spike & losing control of the driver...your system still sees driver but the device never got connected.
When you power up PC you load drivers 1st & then look for device . . .But coming out of standby. . . PC looses driver control of this device & when it looks for driver its gone & you cannot convince your PC that is there . . .
Try removing USB cable while in Standby . . . .Bring out of Standby & then reconnect USB cable . . .this may reduce the effect of the power spike. . .Maybe!
It also could be related to a wiring problem if using front ports.. . . There are 3 ground wires in the wire cable – only 2 are used . . .may have wrong one connected so the suggestion from: dsenette may have some merit. . . hence shedding some light on that problem. . . .
It could be related to USB Wake UP Feature if you are not meeting the 2 amp minimum requirement. How many USB devices do you have?
Please List. .&. .Try the standby – remove USB – Activate & see if USB Memory stick is OK
To darqblue: Not familiar with Laptops . . .Is your mouse USB try removing while in standby without activating . . . of course you may not be able to activate without a mouse...can you use a keystroke?
Edited by Jack123, 19 July 2005 - 03:03 PM.