Lantronix DSTni-EX User Manual

50 

/// 0  0 

Disable 

endpoint. 

/// 

0 

1 

Enable endpoint for TX transfer only. 

/// 

1 

0 

Enable endpoint for RX transfer only. 

1 

1 

1 

Enable endpoint for RX and TX transfers. 

0 

1 

1 

Enable endpoint for RX and TX and control (SETUP) 
transfers. 

 

A unique feature of the USB core is its host mode logic. This logic lets devices such as digital 
cameras and palmtop computers work as a USB host controller. Host mode lets a peripheral 
such as a digital camera connect directly to a USB-compliant printer. Digital photos can then be 
easily printed without having to upload them to a PC. Similarly, with palmtop computer 
applications, a USB-compliant keyboard/mouse can connect to the palmtop computer for easy 
interaction. 

Host mode is designed for handheld-portable devices, allowing easy connection to simple 
Human Interface Device (HID)-class devices such as printers and keyboards. It is not intended 
to perform the functions of full Open Host Controller Interface (OHCI)- or Universal Host 
Controller Interface (UHCI)-compatible host controllers found on PC motherboards.  

Host mode allows bulk, isochronous, interrupt and control transfers. Bulk data transfers are 
performed at nearly the full USB bus bandwidth. Support is provided for ISO transfers; however, 
the number of ISO streams that can be practically supported depends on the interrupt latency of 
the microprocessor servicing the token-done interrupts from the SIE. Custom drivers must be 
written to support host mode. The USB is not supported by Windows 98 as a USB host 
controller. 

The USB core can operate as either a target device or in host mode. It cannot operate in both 
modes simultaneously. 

To enable host mode, set the HOST_MODE_EN bit in the Status register (see Status Register 
on page 43). Host mode also uses the following registers: 

 

 

During host mode, only endpoint zero is used. Software must disable all other endpoints.