Question about USB port

**510SX** · 08-15-2005, 07:54 PM

My laptop has one PCMCIA slot and one USB port open. If I am going to use the laptop for my carputer project. I probably need more PCMCIA or USB port.

My question is; can you use USB hub for all the input device such as mouse, touch screen, blue tooth... and all come back to the single usb port in the laptop?

**viguera** · 08-15-2005, 07:58 PM

Originally Posted by 510SX

My question is; can you use USB hub for all the input device such as mouse, touch screen, blue tooth... and all come back to the single usb port in the laptop?

You can, but depending on the draw you might need a powered USB hub. I can use a GPS, gyration kb/mouse receiver and touchscreen on a hub powered by the bus, but when I added a video capture device (for FrodoCam), Windows let me know I was out of juice and I needed to use a powered hub.

You can easily see how much juice you're using and what's left from the properties of the usb root in the device manager. If you have anything plugged in, it will tell you how much power it's using and what you have left.

**thanatos106** · 08-15-2005, 07:59 PM

Yes you can.... you can also get a PCMCIA USB hub card. (up to 4 usb ports)

**Gunmaster** · 08-15-2005, 08:08 PM

Hub would be better. I would keep the pcmcia slot open.

**thanatos106** · 08-15-2005, 08:12 PM

The problem with the hub is that you have to provide power to it, make one of those dc-dc or buy one or throu his PSU. the PCMCIA is build in to the laptop (the same that with my MII 12K)

But well at least he knows that he got some choices.

Thanatos.

**Gunmaster** · 08-15-2005, 08:27 PM

Originally Posted by thanatos106

The problem with the hub is that you have to provide power to it, make one of those dc-dc or buy one or throu his PSU. the PCMCIA is build in to the laptop (the same that with my MII 12K)

But well at least he knows that he got some choices.

Thanatos.

Dont they make hubs that are powered through the usb cable?

**viguera** · 08-15-2005, 08:35 PM

Originally Posted by Gunmaster

Dont they make hubs that are powered through the usb cable?

Most hubs are self-powered (well, by the root hub on the PC anyway

), but some can use external juice from a brick. Depends on what you buy, I suppose... I got the smallest one I could find that was bus-powered, because I didn't want to worry about yet another thing to power from the car. The pros (size and bus-powered) to me outweight the cons (you can't bug out and put everything you want on it because of the limited juice).

In his case though, I think a hub is a better option. It will keep the PCMCIA port open, and can be expanded or replaced down the line. If he gets a PCMCIA USB controller, and later on he needs more ports, he's gonna have to get another hub anyway... and if he needs the port for something (NIC, firewire, whatever) then he's definitely *** out...

**shamyday** · 08-15-2005, 08:57 PM

it's been discussed before, so you should search for it, but you should watch out when coupling usb2.0 and usb1.1 devices when you need the speed of a 2.0. In most cases, the hub will limit the speed to that of the slowest device.

**NeckPayne** · 08-15-2005, 10:33 PM

The beauty of USB is you can plug up to 127 devices into one port.

The other question, is a matter of power, amperage. Yes there is a 5v line for the USB, the current output of that line is only going to be so much as a result of the power capabilities of the USB port. When you start adding multiple devices, though every device gets 5v (loads in parallel) they are sharing the amperage coming out of the original port, eventually with enough devices, you'll exceed the power capabilities of the original port. That's why you need powered hubs.

Several have also mentioned that the problem with hubs downconverting all devices to 1.1 when a single 1.1 device is plugged in is the defining difference between the $45 and $5 hubs. YMMV.

**kiltjim** · 08-15-2005, 11:14 PM

NeckPayne said it best I think. A single USB (and this may depend on mobo) is only supposed to allow upto 500 mA. I know on some computer you will get a warning if you exceed this. Some just plain don't work. And then theres some computers that don't live by this, and will allow you to source as much current as you need. I don't know which is worse...