Figure 17-2. Usb Communication Endpoints; Table 17-1. Endpoint Function - Sharp LH79524 User Manual

Universal Serial Bus Device
17.1.1 Endpoints
Communications take place between the Host and Device via data 'pipes'. Multiple com-
munication pipes can exist between a Host and the Client, with each pipe terminating at
the USB Device in an 'endpoint'.
The USB Device has four endpoints, Endpoint 0 (EP0) through Endpoint 3 (EP3). Each
endpoint has a FIFO to facilitate communications. Figure 17-2 is a graphical representa-
tion of these endpoints, and Table 17-1 describes the endpoints and their function. Note
that the direction type associated with the endpoints is from the perspective of the Host.
For example, an IN endpoint terminates a data pipe transferring data from the LH79524/
LH79525 to the Host.
ENDPOINT
EP0
EP1
EP2
EP3
17-2
CONTROL PIPE
DATA PIPE
USB HOST
ISO DATA PIPE
INTERRUPT PIPE

Figure 17-2. USB Communication Endpoints

Table 17-1. Endpoint Function

TYPE
Control endpoint. EP0 is always enabled when power is applied. The
IN/OUT
USB Host uses EP0 for initial configuration and for control.
EP1 handles Bulk IN and OUT transfers. Transfers of large data blocks
IN/OUT from the USB Device into the USB Host take place through the pipe ter-
minating in EP1.
EP2 handles Isochronous IN and OUT transfers. Transfers of large data
IN/OUT blocks from the USB Host into the USB Device take place through the
pipe terminating in EP2.
EP3 handles Interrupt IN transfers. The EP3 pipe allows the USB
IN
Device to interrupt the USB Host.
Version 1.0
LH79524/LH79525 User's Guide
LH79525 USB DEVICE
ENDPOINT 0 (IN and OUT)
32-BYTE SHARED FIFO
ENDPOINT 1 (IN and OUT)
128-BYTE FIFO × 2
ENDPOINT 2 (IN and OUT ISO)
1024-BYTE FIFO × 2
ENDPOINT 3 (IN)
128-BYTE FIFO
FUNCTION
LH79525-58