K60P100M100SF2RM Datasheet, PDF (1237/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Chapter 45 Universal Serial Bus OTG Controller (USBOTG)
System Memory
BDT Page
BDT_PAGE Registers END_POINT IN ODD 000
Current
Endpoint
BDT
Buffer in Memory
Start of Buffer
Figure 45-3. Buffer Descriptor Table
45.3.2 Rx vs. Tx as a USB Target Device or USB Host
The USB-FS core uses software control to switch between two modes of operation:
• USB target device
• USB hosts
In either mode, USB host or USB target device, the same data paths and buffer
descriptors are used for the transmission and reception of data. For this reason, a USB-FS
core centric nomenclature is used to describe the direction of the data transfer between
the USB-FS core and the USB:
Rx (or receive)
describes transfers that move data from the USB to memory.
Tx (or transmit)
describes transfers that move data from memory to the USB.
The following table shows how the data direction corresponds to the USB token type in
host and target device applications.
Table 45-1. Data Direction for USB Host or USB Target
Rx
Tx
Device
OUT or Setup
IN
Table continues on the next page...
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
1237