What are the main differences in hardware aspect of USB host and device?

[stephen_h]

Hi all,

I want to check that what is the main differences in hardware aspect on the USB host and device. As this catalog of component has a large diferent in pricing.

 

[rakko]

Re: USB Host and Device

there are two parts to a usb system 1. a host controller and 2. a device controller also called usb function. USB device is much smaller in size than a host mostly because they act as slave to the usb host controller and don't need much hardware. USB host on the other hand needs to interface to the the cpu and also be able to control poll the usb devices to initiate transactions to/from device in case devices need it. all this makes usb hosts much bigger and more expensive than usb device. If you look at a pci usb host controller chip in your pc and compare it to the usb device controller in your usb mouse, your see the usb host chip is much bigger than the device.