PIC24FJ256GB108-I Datasheet, PDF (207/352 Pages) Microchip Technology – 64/80/100-Pin, 16-Bit Flash Microcontrollers with USB On-The-Go (OTG)

PIC24FJ256GB110 FAMILY
18.0 UNIVERSAL SERIAL BUS WITH
ON-THE-GO SUPPORT (USB
OTG)
Note:
This data sheet summarizes the features
of this group of PIC24F devices. It is not
intended to be a comprehensive reference
source. For more information, refer to the
“PIC24F Family Reference Manual”,
Section 27. “USB On-The-Go (OTG)”.
PIC24FJ256GB110 family devices contain a full-speed
and low-speed compatible, On-The-Go (OTG) USB
Serial Interface Engine (SIE). The OTG capability
allows the device to act either as a USB peripheral
device or as a USB embedded host with limited host
capabilities. The OTG capability allows the device to
dynamically switch from device to host operation using
OTG’s Host Negotiation Protocol (HNP).
For more details on OTG operation, refer to the
“On-The-Go Supplement to the USB 2.0 Specification”,
published by the USB-IF. For more details on USB oper-
ation, refer to the “Universal Serial Bus Specification”,
v2.0.
The USB OTG module offers these features:
• USB functionality in Device and Host modes, and
OTG capabilities for application-controlled mode
switching
• Software-selectable module speeds of full speed
(12 Mbps) or low speed (1.5 Mbps, available in
Host mode only)
• Support for all four USB transfer types: control,
interrupt, bulk and isochronous
• 16 bidirectional endpoints for a total of 32 unique
endpoints
• DMA interface for data RAM access
• Queues up to sixteen unique endpoint transfers
without servicing
• Integrated, on-chip USB transceiver, with support
for off-chip transceivers via a digital interface:
• Integrated VBUS generation with on-chip
comparators and boost generation, and support of
external VBUS comparators and regulators
through a digital interface
• Configurations for on-chip bus pull-up and
pull-down resistors
A simplified block diagram of the USB OTG module is
shown in Figure 18-1.
The USB OTG module can function as a USB periph-
eral device or as a USB host, and may dynamically
switch between Device and Host modes under
software control. In either mode, the same data paths
and buffer descriptors are used for the transmission
and reception of data.
In discussing USB operation, this section will use a
controller-centric nomenclature for describing the direc-
tion of the data transfer between the microcontroller and
the USB. Rx (Receive) will be used to describe transfers
that move data from the USB to the microcontroller, and
Tx (Transmit) will be used to describe transfers that
move data from the microcontroller to the USB.
Table 18-1 shows the relationship between data
direction in this nomenclature and the USB tokens
exchanged.
TABLE 18-1:
CONTROLLER-CENTRIC
DATA DIRECTION FOR USB
HOST OR TARGET
USB Mode
Direction
Rx
Tx
Device
Host
OUT or SETUP
IN
IN
OUT or SETUP
This chapter presents the most basic operations
needed to implement USB OTG functionality in an
application. A complete and detailed discussion of the
USB protocol and its OTG supplement are beyond the
scope of this data sheet. It is assumed that the user
already has a basic understanding of USB architecture
and the latest version of the protocol.
Not all steps for proper USB operation (such as device
enumeration) are presented here. It is recommended
that application developers use an appropriate device
driver to implement all of the necessary features.
Microchip provides a number of application-specific
resources, such as USB firmware and driver support.
Refer to www.microchip.com for the latest firmware and
driver support.
 2009 Microchip Technology Inc.
DS39897C-page 207